Ascidians Black & White Stock Photos
ASCIDIANS. Leathery fixed sea-squirt, Microcosmus 1896 old antique print Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-leathery-fixed-sea-squirt-microcosmus-1896-old-antique-print-image185109421.htmlRFMN4CXN–ASCIDIANS. Leathery fixed sea-squirt, Microcosmus 1896 old antique print
. Outlines of zoology. glandular endostyle, and adorsal fold (Tunicates) or groove {Amphioxus), connectedanteriorly to the endostyle by means of a ciliated band. On the other hand, the Ascidians differ from the lanceletsin many ways, e.g. the sessile habit, the presence of thetest, of a heart, and of genital ducts; the absence of seg-mentation, of nephridia, and any trace of ccelom in theadult; the U-shaped alimentary canal; the power of budding,so common in sedentary animals; and the hermaphroditism. The detailed study of development yields similar seriesof facts — marked resemblances coupled Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/outlines-of-zoology-glandular-endostyle-and-adorsal-fold-tunicates-or-groove-amphioxus-connectedanteriorly-to-the-endostyle-by-means-of-a-ciliated-band-on-the-other-hand-the-ascidians-differ-from-the-lanceletsin-many-ways-eg-the-sessile-habit-the-presence-of-thetest-of-a-heart-and-of-genital-ducts-the-absence-of-seg-mentation-of-nephridia-and-any-trace-of-ccelom-in-theadult-the-u-shaped-alimentary-canal-the-power-of-buddingso-common-in-sedentary-animals-and-the-hermaphroditism-the-detailed-study-of-development-yields-similar-seriesof-facts-marked-resemblances-coupled-image337136992.htmlRM2AGDWJT–. Outlines of zoology. glandular endostyle, and adorsal fold (Tunicates) or groove {Amphioxus), connectedanteriorly to the endostyle by means of a ciliated band. On the other hand, the Ascidians differ from the lanceletsin many ways, e.g. the sessile habit, the presence of thetest, of a heart, and of genital ducts; the absence of seg-mentation, of nephridia, and any trace of ccelom in theadult; the U-shaped alimentary canal; the power of budding,so common in sedentary animals; and the hermaphroditism. The detailed study of development yields similar seriesof facts — marked resemblances coupled
. Animal activities; a first book in zoo?logy. Zoology; Animal behavior. 246 /tNIM/IL ACTiyiTIES. Embryology. The sea-squirts, called also ascidians and tunicates, were once classified as belonging to the MoUusca, and later to the Vermes. Zoologists now class these animals with the Chordata, because a study of their development shows decided vertebrate charac- teristics, which disappear with maturity. The larval forms of some of these animals resemble the tadpoles of frogs, showing the notochord and the gill-slits so characteristic of vertebrate animals. Here it is the. Fig. 199.—The Archsopte Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-activities-a-first-book-in-zoology-zoology-animal-behavior-246-tnimil-actiyities-embryology-the-sea-squirts-called-also-ascidians-and-tunicates-were-once-classified-as-belonging-to-the-mouusca-and-later-to-the-vermes-zoologists-now-class-these-animals-with-the-chordata-because-a-study-of-their-development-shows-decided-vertebrate-charac-teristics-which-disappear-with-maturity-the-larval-forms-of-some-of-these-animals-resemble-the-tadpoles-of-frogs-showing-the-notochord-and-the-gill-slits-so-characteristic-of-vertebrate-animals-here-it-is-the-fig-199the-archsopte-image216366531.htmlRMPG09M3–. Animal activities; a first book in zoo?logy. Zoology; Animal behavior. 246 /tNIM/IL ACTiyiTIES. Embryology. The sea-squirts, called also ascidians and tunicates, were once classified as belonging to the MoUusca, and later to the Vermes. Zoologists now class these animals with the Chordata, because a study of their development shows decided vertebrate charac- teristics, which disappear with maturity. The larval forms of some of these animals resemble the tadpoles of frogs, showing the notochord and the gill-slits so characteristic of vertebrate animals. Here it is the. Fig. 199.—The Archsopte
ASCIDIANS. Pear-shaped ascidian, Hypobythius 1896 old antique print picture Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-pear-shaped-ascidian-hypobythius-1896-old-antique-print-picture-image185109419.htmlRFMN4CXK–ASCIDIANS. Pear-shaped ascidian, Hypobythius 1896 old antique print picture
The principles of biology . common support, and establish among them a more decidedcommunity of nutrition. Among the Ascidians, another order of the Molluscoida, thisgeneral law of morphological composition is once more dis-played. Each of these creatures subsists on the nutritiveparticles contained in the water which it draws in throughone orifice and sends out through another ; and it may thussubsist either alone, or in connexion with others that arein some cases loosely aggregated and in other cases closelyaggregated. Fig. 156, Fhallusia mentula, is one of the soli-. tary forms. A type in w Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-principles-of-biology-common-support-and-establish-among-them-a-more-decidedcommunity-of-nutrition-among-the-ascidians-another-order-of-the-molluscoida-thisgeneral-law-of-morphological-composition-is-once-more-dis-played-each-of-these-creatures-subsists-on-the-nutritiveparticles-contained-in-the-water-which-it-draws-in-throughone-orifice-and-sends-out-through-another-and-it-may-thussubsist-either-alone-or-in-connexion-with-others-that-arein-some-cases-loosely-aggregated-and-in-other-cases-closelyaggregated-fig-156-fhallusia-mentula-is-one-of-the-soli-tary-forms-a-type-in-w-image339996165.htmlRM2AN44G5–The principles of biology . common support, and establish among them a more decidedcommunity of nutrition. Among the Ascidians, another order of the Molluscoida, thisgeneral law of morphological composition is once more dis-played. Each of these creatures subsists on the nutritiveparticles contained in the water which it draws in throughone orifice and sends out through another ; and it may thussubsist either alone, or in connexion with others that arein some cases loosely aggregated and in other cases closelyaggregated. Fig. 156, Fhallusia mentula, is one of the soli-. tary forms. A type in w
. Zoology : for students and general readers . Zoology. HABITS OF ASCIDIANS. 197 Balanoglossus, is a provisional one. In a diagram chowing tlie classification, i.e., the affinities of tlio different classes of animals, the Tunicates may be represented as an independent branch sent off possibly from the Trematode stem, running parallel to the worms, near Balanoglossus, and ending a little below the level of AmpJtioxus. They have certainly few niollnscan features, what do exist being superficial, and nothing to remind iis closely of the Pohjzoa or Bracliiopods, and the class is here treated of b Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-habits-of-ascidians-197-balanoglossus-is-a-provisional-one-in-a-diagram-chowing-tlie-classification-ie-the-affinities-of-tlio-different-classes-of-animals-the-tunicates-may-be-represented-as-an-independent-branch-sent-off-possibly-from-the-trematode-stem-running-parallel-to-the-worms-near-balanoglossus-and-ending-a-little-below-the-level-of-ampjtioxus-they-have-certainly-few-niollnscan-features-what-do-exist-being-superficial-and-nothing-to-remind-iis-closely-of-the-pohjzoa-or-bracliiopods-and-the-class-is-here-treated-of-b-image216394308.htmlRMPG1H44–. Zoology : for students and general readers . Zoology. HABITS OF ASCIDIANS. 197 Balanoglossus, is a provisional one. In a diagram chowing tlie classification, i.e., the affinities of tlio different classes of animals, the Tunicates may be represented as an independent branch sent off possibly from the Trematode stem, running parallel to the worms, near Balanoglossus, and ending a little below the level of AmpJtioxus. They have certainly few niollnscan features, what do exist being superficial, and nothing to remind iis closely of the Pohjzoa or Bracliiopods, and the class is here treated of b
ASCIDIAN. Cartilaginous fixed sea-squirt, Phallusia 1896 old antique print Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidian-cartilaginous-fixed-sea-squirt-phallusia-1896-old-antique-print-image185109418.htmlRFMN4CXJ–ASCIDIAN. Cartilaginous fixed sea-squirt, Phallusia 1896 old antique print
First lesson in zoology : adapted for use in schools . mentalvertebrate marks, that of a rudimentary backbone, i.e., anotocord, with the nervous system placed above, and theother internal organs below. But there is a group of animals which partly bridge overthe gap between the lancelet and the worms. These are the sea-squirts or ascidians (Fig. 147). Oneof them, called Appendicularin, is like a tadpole in generalappearance, while the larvae of most ofthem are tadpole-shaped, as in Fig. 148. Inthe infant ascidian the tail is supported bya gristly rod {u), extending into the chest,and correspond Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/first-lesson-in-zoology-adapted-for-use-in-schools-mentalvertebrate-marks-that-of-a-rudimentary-backbone-ie-anotocord-with-the-nervous-system-placed-above-and-theother-internal-organs-below-but-there-is-a-group-of-animals-which-partly-bridge-overthe-gap-between-the-lancelet-and-the-worms-these-are-the-sea-squirts-or-ascidians-fig-147-oneof-them-called-appendicularin-is-like-a-tadpole-in-generalappearance-while-the-larvae-of-most-ofthem-are-tadpole-shaped-as-in-fig-148-inthe-infant-ascidian-the-tail-is-supported-bya-gristly-rod-u-extending-into-the-chestand-correspond-image339215901.htmlRM2AKTH9H–First lesson in zoology : adapted for use in schools . mentalvertebrate marks, that of a rudimentary backbone, i.e., anotocord, with the nervous system placed above, and theother internal organs below. But there is a group of animals which partly bridge overthe gap between the lancelet and the worms. These are the sea-squirts or ascidians (Fig. 147). Oneof them, called Appendicularin, is like a tadpole in generalappearance, while the larvae of most ofthem are tadpole-shaped, as in Fig. 148. Inthe infant ascidian the tail is supported bya gristly rod {u), extending into the chest,and correspond
. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTIOK BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as MedusiB, swimming Polyps, Ascidians, and such like; quite suddenly the ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two dfiys we sailed without interruption through fields of gigantic Pyrosomata {P.gigantevm, see fig. 71), which swam so c Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-life-as-affected-by-the-natural-conditions-of-existence-animal-ecology-distkibutiok-by-cukeents-279-animal-world-was-remarkably-poor-in-species-and-more-par-ticularly-was-it-devoid-of-all-the-larger-forms-as-medusib-swimming-polyps-ascidians-and-such-like-quite-suddenly-the-ocean-teemed-with-abundant-life-as-we-entered-on-the-warm-mozambique-current-to-the-east-of-the-cape-the-whole-sea-was-literally-covered-with-animals-of-every-kind-and-for-more-than-two-dfiys-we-sailed-without-interruption-through-fields-of-gigantic-pyrosomata-pgigantevm-see-fig-71-which-swam-so-c-image216357849.htmlRMPFYXJ1–. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTIOK BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as MedusiB, swimming Polyps, Ascidians, and such like; quite suddenly the ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two dfiys we sailed without interruption through fields of gigantic Pyrosomata {P.gigantevm, see fig. 71), which swam so c
. Animal activities; a first book in zoo?logy. Zoology; Animal behavior. 246 /tNIM/IL ACTiyiTIES. Embryology. The sea-squirts, called also ascidians and tunicates, were once classified as belonging to the MoUusca, and later to the Vermes. Zoologists now class these animals with the Chordata, because a study of their development shows decided vertebrate charac- teristics, which disappear with maturity. The larval forms of some of these animals resemble the tadpoles of frogs, showing the notochord and the gill-slits so characteristic of vertebrate animals. Here it is the. Fig. 199.—The Archsopte Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-activities-a-first-book-in-zoology-zoology-animal-behavior-246-tnimil-actiyities-embryology-the-sea-squirts-called-also-ascidians-and-tunicates-were-once-classified-as-belonging-to-the-mouusca-and-later-to-the-vermes-zoologists-now-class-these-animals-with-the-chordata-because-a-study-of-their-development-shows-decided-vertebrate-charac-teristics-which-disappear-with-maturity-the-larval-forms-of-some-of-these-animals-resemble-the-tadpoles-of-frogs-showing-the-notochord-and-the-gill-slits-so-characteristic-of-vertebrate-animals-here-it-is-the-fig-199the-archsopte-image232052817.htmlRMRDEWMH–. Animal activities; a first book in zoo?logy. Zoology; Animal behavior. 246 /tNIM/IL ACTiyiTIES. Embryology. The sea-squirts, called also ascidians and tunicates, were once classified as belonging to the MoUusca, and later to the Vermes. Zoologists now class these animals with the Chordata, because a study of their development shows decided vertebrate charac- teristics, which disappear with maturity. The larval forms of some of these animals resemble the tadpoles of frogs, showing the notochord and the gill-slits so characteristic of vertebrate animals. Here it is the. Fig. 199.—The Archsopte
. Zoology : for students and general readers . Zoology. 308 zooLoo y. of several species of Molgula, but it has the five long decid- uous appendages observed in young Molgulm. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 2. Thaliacea.âOi the whole, we may regard this order, represented by Salpa (Fig. 140), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance off the shores of Southern New England, while the others Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-308-zooloo-y-of-several-species-of-molgula-but-it-has-the-five-long-decid-uous-appendages-observed-in-young-molgulm-among-the-compound-ascidians-botryllus-and-botrylloides-have-tailed-young-while-in-other-forms-there-is-no-metamorphosis-de-velopment-being-direct-order-2-thaliaceaoi-the-whole-we-may-regard-this-order-represented-by-salpa-fig-140-and-doliolum-as-comprising-the-more-specialized-forms-of-tunicates-salpa-is-pelagic-one-species-occurring-in-abundance-off-the-shores-of-southern-new-england-while-the-others-image216394290.htmlRMPG1H3E–. Zoology : for students and general readers . Zoology. 308 zooLoo y. of several species of Molgula, but it has the five long decid- uous appendages observed in young Molgulm. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 2. Thaliacea.âOi the whole, we may regard this order, represented by Salpa (Fig. 140), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance off the shores of Southern New England, while the others
![. The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 2SS direct offspring of the present apes; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged on one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'" The Amphioxus which lives in the sand Stock Photo](https://c8.alamy.com/comp/RDJ5JK/the-doctrine-of-descent-and-darwinism-evolution-lowest-vertebrate-animals-2ss-direct-offspring-of-the-present-apes-neither-do-they-infer-from-these-observations-on-the-ascidian-larva-that-vertebrate-animals-are-descended-from-the-ascidians-their-accordance-much-rather-forces-us-to-assume-an-unknown-primordial-vertebrate-family-springing-from-some-branch-of-the-heterogeneous-division-of-the-annulosa-from-these-diverged-on-one-side-the-tes-tacea-who-might-perhaps-be-called-mischanced-vertebrata-and-on-the-other-the-true-vertebrate-animalsquot-the-amphioxus-which-lives-in-the-sand-RDJ5JK.jpg ". The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 2SS direct offspring of the present apes; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged on one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'" The Amphioxus which lives in the sand Stock Photo")
. The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 2SS direct offspring of the present apes; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged on one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'" The Amphioxus which lives in the sand Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-doctrine-of-descent-and-darwinism-evolution-lowest-vertebrate-animals-2ss-direct-offspring-of-the-present-apes-neither-do-they-infer-from-these-observations-on-the-ascidian-larva-that-vertebrate-animals-are-descended-from-the-ascidians-their-accordance-much-rather-forces-us-to-assume-an-unknown-primordial-vertebrate-family-springing-from-some-branch-of-the-heterogeneous-division-of-the-annulosa-from-these-diverged-on-one-side-the-tes-tacea-who-might-perhaps-be-called-mischanced-vertebrata-and-on-the-other-the-true-vertebrate-animalsquot-the-amphioxus-which-lives-in-the-sand-image232124891.htmlRMRDJ5JK–. The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 2SS direct offspring of the present apes; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged on one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'" The Amphioxus which lives in the sand
. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTION BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as Medusa, swimming Polyps, Ascidians, and such like; quite suddenly tho ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two days we sailed without interruption through fields of gigantic Pyrosomata {P.giganteum, see fig. 71), which swam so clo Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-life-as-affected-by-the-natural-conditions-of-existence-animal-ecology-distkibution-by-cukeents-279-animal-world-was-remarkably-poor-in-species-and-more-par-ticularly-was-it-devoid-of-all-the-larger-forms-as-medusa-swimming-polyps-ascidians-and-such-like-quite-suddenly-tho-ocean-teemed-with-abundant-life-as-we-entered-on-the-warm-mozambique-current-to-the-east-of-the-cape-the-whole-sea-was-literally-covered-with-animals-of-every-kind-and-for-more-than-two-days-we-sailed-without-interruption-through-fields-of-gigantic-pyrosomata-pgiganteum-see-fig-71-which-swam-so-clo-image216447562.htmlRMPG4122–. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTION BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as Medusa, swimming Polyps, Ascidians, and such like; quite suddenly tho ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two days we sailed without interruption through fields of gigantic Pyrosomata {P.giganteum, see fig. 71), which swam so clo
![. Science from an easy chair; a second series. Science; Natural history. Fig. 31.—Two kinds of Ascidians or " sea squirts " of Iialf the natural size. A is the kind known as Ascidia mammillata, B is a red- coloured species of the genus Cynthia allied to Ascidia. It shows on distinct prominences the mouth at the top of the sac-like body and the opening of the peri-branchial chamber on the right. Root- like processes of the sac are given off from its lower end and serve to fix it to a rock or stone. the fish and bait, which are so important to them ; the more sapient among them declare Stock Photo](https://c8.alamy.com/comp/RDNW5N/science-from-an-easy-chair-a-second-series-science-natural-history-fig-31two-kinds-of-ascidians-or-quot-sea-squirts-quot-of-iialf-the-natural-size-a-is-the-kind-known-as-ascidia-mammillata-b-is-a-red-coloured-species-of-the-genus-cynthia-allied-to-ascidia-it-shows-on-distinct-prominences-the-mouth-at-the-top-of-the-sac-like-body-and-the-opening-of-the-peri-branchial-chamber-on-the-right-root-like-processes-of-the-sac-are-given-off-from-its-lower-end-and-serve-to-fix-it-to-a-rock-or-stone-the-fish-and-bait-which-are-so-important-to-them-the-more-sapient-among-them-declare-RDNW5N.jpg ". Science from an easy chair; a second series. Science; Natural history. Fig. 31.—Two kinds of Ascidians or " sea squirts " of Iialf the natural size. A is the kind known as Ascidia mammillata, B is a red- coloured species of the genus Cynthia allied to Ascidia. It shows on distinct prominences the mouth at the top of the sac-like body and the opening of the peri-branchial chamber on the right. Root- like processes of the sac are given off from its lower end and serve to fix it to a rock or stone. the fish and bait, which are so important to them ; the more sapient among them declare Stock Photo")
. Science from an easy chair; a second series. Science; Natural history. Fig. 31.—Two kinds of Ascidians or " sea squirts " of Iialf the natural size. A is the kind known as Ascidia mammillata, B is a red- coloured species of the genus Cynthia allied to Ascidia. It shows on distinct prominences the mouth at the top of the sac-like body and the opening of the peri-branchial chamber on the right. Root- like processes of the sac are given off from its lower end and serve to fix it to a rock or stone. the fish and bait, which are so important to them ; the more sapient among them declare Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/science-from-an-easy-chair-a-second-series-science-natural-history-fig-31two-kinds-of-ascidians-or-quot-sea-squirts-quot-of-iialf-the-natural-size-a-is-the-kind-known-as-ascidia-mammillata-b-is-a-red-coloured-species-of-the-genus-cynthia-allied-to-ascidia-it-shows-on-distinct-prominences-the-mouth-at-the-top-of-the-sac-like-body-and-the-opening-of-the-peri-branchial-chamber-on-the-right-root-like-processes-of-the-sac-are-given-off-from-its-lower-end-and-serve-to-fix-it-to-a-rock-or-stone-the-fish-and-bait-which-are-so-important-to-them-the-more-sapient-among-them-declare-image232206065.htmlRMRDNW5N–. Science from an easy chair; a second series. Science; Natural history. Fig. 31.—Two kinds of Ascidians or " sea squirts " of Iialf the natural size. A is the kind known as Ascidia mammillata, B is a red- coloured species of the genus Cynthia allied to Ascidia. It shows on distinct prominences the mouth at the top of the sac-like body and the opening of the peri-branchial chamber on the right. Root- like processes of the sac are given off from its lower end and serve to fix it to a rock or stone. the fish and bait, which are so important to them ; the more sapient among them declare
![. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photo](https://c8.alamy.com/comp/PG1H3P/zoology-for-students-and-general-readers-zoology-development-of-asgidians-203-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perojjjiora-the-original-parent-ascidian-throws-ofe-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-PG1H3P.jpg ". Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photo")
. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-development-of-asgidians-203-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perojjjiora-the-original-parent-ascidian-throws-ofe-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-image216394298.htmlRMPG1H3P–. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians
![. British reptiles and batrachians. Amphibians; Reptiles. 44 REPTILES AND BATRACHIANS. found in the larval Ascidians, or Tunicates. But unfortunately the Tunicates are such very degenerate vertebrates that very little can be got from them for the elucidation of the problem." Of that " little " they can be made to suit our purpose by com- paring the metamorphosis which they undergo with that of the frog, and thus afford us an example of that " higher " and " lower " development, and also some idea of the part which an embryo plays in this. Both they and the fr Stock Photo](https://c8.alamy.com/comp/RDR3WN/british-reptiles-and-batrachians-amphibians-reptiles-44-reptiles-and-batrachians-found-in-the-larval-ascidians-or-tunicates-but-unfortunately-the-tunicates-are-such-very-degenerate-vertebrates-that-very-little-can-be-got-from-them-for-the-elucidation-of-the-problemquot-of-that-quot-little-quot-they-can-be-made-to-suit-our-purpose-by-com-paring-the-metamorphosis-which-they-undergo-with-that-of-the-frog-and-thus-afford-us-an-example-of-that-quot-higher-quot-and-quot-lower-quot-development-and-also-some-idea-of-the-part-which-an-embryo-plays-in-this-both-they-and-the-fr-RDR3WN.jpg ". British reptiles and batrachians. Amphibians; Reptiles. 44 REPTILES AND BATRACHIANS. found in the larval Ascidians, or Tunicates. But unfortunately the Tunicates are such very degenerate vertebrates that very little can be got from them for the elucidation of the problem." Of that " little " they can be made to suit our purpose by com- paring the metamorphosis which they undergo with that of the frog, and thus afford us an example of that " higher " and " lower " development, and also some idea of the part which an embryo plays in this. Both they and the fr Stock Photo")
. British reptiles and batrachians. Amphibians; Reptiles. 44 REPTILES AND BATRACHIANS. found in the larval Ascidians, or Tunicates. But unfortunately the Tunicates are such very degenerate vertebrates that very little can be got from them for the elucidation of the problem." Of that " little " they can be made to suit our purpose by com- paring the metamorphosis which they undergo with that of the frog, and thus afford us an example of that " higher " and " lower " development, and also some idea of the part which an embryo plays in this. Both they and the fr Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/british-reptiles-and-batrachians-amphibians-reptiles-44-reptiles-and-batrachians-found-in-the-larval-ascidians-or-tunicates-but-unfortunately-the-tunicates-are-such-very-degenerate-vertebrates-that-very-little-can-be-got-from-them-for-the-elucidation-of-the-problemquot-of-that-quot-little-quot-they-can-be-made-to-suit-our-purpose-by-com-paring-the-metamorphosis-which-they-undergo-with-that-of-the-frog-and-thus-afford-us-an-example-of-that-quot-higher-quot-and-quot-lower-quot-development-and-also-some-idea-of-the-part-which-an-embryo-plays-in-this-both-they-and-the-fr-image232233281.htmlRMRDR3WN–. British reptiles and batrachians. Amphibians; Reptiles. 44 REPTILES AND BATRACHIANS. found in the larval Ascidians, or Tunicates. But unfortunately the Tunicates are such very degenerate vertebrates that very little can be got from them for the elucidation of the problem." Of that " little " they can be made to suit our purpose by com- paring the metamorphosis which they undergo with that of the frog, and thus afford us an example of that " higher " and " lower " development, and also some idea of the part which an embryo plays in this. Both they and the fr
. Natural history of animals. Containing brief descriptions of the animals figured on Tenney's Natural history tablets, but complete without the tablets. Zoology. Reduced. Fig. 457. — Pholas. New England and eastward.. Fig. 458. — Tunicate. TUNICATES. These are mollusks which have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clusters, attached by a stem to sea- weed, rocks, or floating timber. They vary from the size of a pea to an inch or more in diameter. They are sometimes called Ascidians, from a word which means a leather lag.. Please note that these image Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/natural-history-of-animals-containing-brief-descriptions-of-the-animals-figured-on-tenneys-natural-history-tablets-but-complete-without-the-tablets-zoology-reduced-fig-457-pholas-new-england-and-eastward-fig-458-tunicate-tunicates-these-are-mollusks-which-have-no-shell-but-are-covered-with-a-tough-tunic-or-skin-sometimes-they-grow-in-clusters-attached-by-a-stem-to-sea-weed-rocks-or-floating-timber-they-vary-from-the-size-of-a-pea-to-an-inch-or-more-in-diameter-they-are-sometimes-called-ascidians-from-a-word-which-means-a-leather-lag-please-note-that-these-image-image216365918.htmlRMPG08X6–. Natural history of animals. Containing brief descriptions of the animals figured on Tenney's Natural history tablets, but complete without the tablets. Zoology. Reduced. Fig. 457. — Pholas. New England and eastward.. Fig. 458. — Tunicate. TUNICATES. These are mollusks which have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clusters, attached by a stem to sea- weed, rocks, or floating timber. They vary from the size of a pea to an inch or more in diameter. They are sometimes called Ascidians, from a word which means a leather lag.. Please note that these image
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 112 DEVELOPMENT OF AMPHIOXUS. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate gastrula from the Ascidians up to the highest craniate forms. In the Inverte- brates (Anne Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-112-development-of-amphioxus-while-the-opposite-side-is-flattened-this-is-an-indication-that-dorso-ventral-differentiation-has-taken-place-since-the-flattened-side-marks-the-dorsum-or-back-of-the-embryo-while-the-convex-side-is-ventral-it-may-be-seen-further-that-the-blastopore-is-inclined-towards-the-dorsal-side-of-the-embryo-the-dorsal-inclination-of-the-blastopore-is-eminently-characteristic-of-the-vertebrate-gastrula-from-the-ascidians-up-to-the-highest-craniate-forms-in-the-inverte-brates-anne-image232347510.htmlRMRE09HA–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 112 DEVELOPMENT OF AMPHIOXUS. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate gastrula from the Ascidians up to the highest craniate forms. In the Inverte- brates (Anne
![. A manual of zoology. Zoology. 446 CIIORDATA CviUliij.'-' !N[oi.c.ri IP.F, oral opening, six-lobed, airial foiir-lobed. }ro!i;iihi* K:i:;yr,::' Sub Oixlcr II. S XASCIl'LK. Coinpound ascidians consisling of numerous small individuals imbedded in a eommon tunie. Usually ^lii;. 502) the indiiduals of a eolon' are diided into small groups, the oral openings of a groui) forming a rosette around a eommon central atrium. Dislaplia,'^ Lcpto-. FiC'. 500.â^)e^"e]oylment of an Ascidian (after KuplTcr and Ko"ali: larva, just hatchcil; 2, eross-section through the tail of a shghtly younger Stock Photo](https://c8.alamy.com/comp/PG3NHX/a-manual-of-zoology-zoology-446-ciiordata-cviuliij-!n-oicri-ipf-oral-opening-six-lobed-airial-foiir-lobed-ro!iiihi-kiyr-sub-oixlcr-ii-s-xascillk-coinpound-ascidians-consisling-of-numerous-small-individuals-imbedded-in-a-eommon-tunie-usually-lii-502-the-indiiduals-of-a-eolon-are-diided-into-small-groups-the-oral-openings-of-a-groui-forming-a-rosette-around-a-eommon-central-atrium-dislaplia-lcpto-fic-500equote-oylment-of-an-ascidian-after-kupltcr-and-koquotali-larva-just-hatchcil-2-eross-section-through-the-tail-of-a-shghtly-younger-PG3NHX.jpg ". A manual of zoology. Zoology. 446 CIIORDATA CviUliij.'-' !N[oi.c.ri IP.F, oral opening, six-lobed, airial foiir-lobed. }ro!i;iihi* K:i:;yr,::' Sub Oixlcr II. S XASCIl'LK. Coinpound ascidians consisling of numerous small individuals imbedded in a eommon tunie. Usually ^lii;. 502) the indiiduals of a eolon' are diided into small groups, the oral openings of a groui) forming a rosette around a eommon central atrium. Dislaplia,'^ Lcpto-. FiC'. 500.â^)e^"e]oylment of an Ascidian (after KuplTcr and Ko"ali: larva, just hatchcil; 2, eross-section through the tail of a shghtly younger Stock Photo")
. A manual of zoology. Zoology. 446 CIIORDATA CviUliij.'-' !N[oi.c.ri IP.F, oral opening, six-lobed, airial foiir-lobed. }ro!i;iihi* K:i:;yr,::' Sub Oixlcr II. S XASCIl'LK. Coinpound ascidians consisling of numerous small individuals imbedded in a eommon tunie. Usually ^lii;. 502) the indiiduals of a eolon' are diided into small groups, the oral openings of a groui) forming a rosette around a eommon central atrium. Dislaplia,'^ Lcpto-. FiC'. 500.â^)e^"e]oylment of an Ascidian (after KuplTcr and Ko"ali: larva, just hatchcil; 2, eross-section through the tail of a shghtly younger Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-manual-of-zoology-zoology-446-ciiordata-cviuliij-!n-oicri-ipf-oral-opening-six-lobed-airial-foiir-lobed-ro!iiihi-kiyr-sub-oixlcr-ii-s-xascillk-coinpound-ascidians-consisling-of-numerous-small-individuals-imbedded-in-a-eommon-tunie-usually-lii-502-the-indiiduals-of-a-eolon-are-diided-into-small-groups-the-oral-openings-of-a-groui-forming-a-rosette-around-a-eommon-central-atrium-dislaplia-lcpto-fic-500equote-oylment-of-an-ascidian-after-kupltcr-and-koquotali-larva-just-hatchcil-2-eross-section-through-the-tail-of-a-shghtly-younger-image216441734.htmlRMPG3NHX–. A manual of zoology. Zoology. 446 CIIORDATA CviUliij.'-' !N[oi.c.ri IP.F, oral opening, six-lobed, airial foiir-lobed. }ro!i;iihi* K:i:;yr,::' Sub Oixlcr II. S XASCIl'LK. Coinpound ascidians consisling of numerous small individuals imbedded in a eommon tunie. Usually ^lii;. 502) the indiiduals of a eolon' are diided into small groups, the oral openings of a groui) forming a rosette around a eommon central atrium. Dislaplia,'^ Lcpto-. FiC'. 500.â^)e^"e]oylment of an Ascidian (after KuplTcr and Ko"ali: larva, just hatchcil; 2, eross-section through the tail of a shghtly younger
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. W'i IV. THE ASCIDIANS. The Ascidians, Tunicates, or sea-squirts, as they arc indifferently called, constitute one of the most clearly defined and yet most heterogeneous groups of animals which it is possible to imagine. There is a great variety of families, genera, and species occurring all the world over, and in all depths of the ocean from the tide-marks to the profoundest depths. Most of them are sedentary animals, remaining fixed all their lifetim Stock Photo](https://c8.alamy.com/comp/RJ1762/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-wi-iv-the-ascidians-the-ascidians-tunicates-or-sea-squirts-as-they-arc-indifferently-called-constitute-one-of-the-most-clearly-defined-and-yet-most-heterogeneous-groups-of-animals-which-it-is-possible-to-imagine-there-is-a-great-variety-of-families-genera-and-species-occurring-all-the-world-over-and-in-all-depths-of-the-ocean-from-the-tide-marks-to-the-profoundest-depths-most-of-them-are-sedentary-animals-remaining-fixed-all-their-lifetim-RJ1762.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. W'i IV. THE ASCIDIANS. The Ascidians, Tunicates, or sea-squirts, as they arc indifferently called, constitute one of the most clearly defined and yet most heterogeneous groups of animals which it is possible to imagine. There is a great variety of families, genera, and species occurring all the world over, and in all depths of the ocean from the tide-marks to the profoundest depths. Most of them are sedentary animals, remaining fixed all their lifetim Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. W'i IV. THE ASCIDIANS. The Ascidians, Tunicates, or sea-squirts, as they arc indifferently called, constitute one of the most clearly defined and yet most heterogeneous groups of animals which it is possible to imagine. There is a great variety of families, genera, and species occurring all the world over, and in all depths of the ocean from the tide-marks to the profoundest depths. Most of them are sedentary animals, remaining fixed all their lifetim Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-wi-iv-the-ascidians-the-ascidians-tunicates-or-sea-squirts-as-they-arc-indifferently-called-constitute-one-of-the-most-clearly-defined-and-yet-most-heterogeneous-groups-of-animals-which-it-is-possible-to-imagine-there-is-a-great-variety-of-families-genera-and-species-occurring-all-the-world-over-and-in-all-depths-of-the-ocean-from-the-tide-marks-to-the-profoundest-depths-most-of-them-are-sedentary-animals-remaining-fixed-all-their-lifetim-image234826202.htmlRMRJ1762–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. W'i IV. THE ASCIDIANS. The Ascidians, Tunicates, or sea-squirts, as they arc indifferently called, constitute one of the most clearly defined and yet most heterogeneous groups of animals which it is possible to imagine. There is a great variety of families, genera, and species occurring all the world over, and in all depths of the ocean from the tide-marks to the profoundest depths. Most of them are sedentary animals, remaining fixed all their lifetim
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. A ij„ii m "Si. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate yastrula from the Ascidians up to the high Stock Photo](https://c8.alamy.com/comp/RJ26RH/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-a-ijii-m-quotsi-while-the-opposite-side-is-flattened-this-is-an-indication-that-dorso-ventral-differentiation-has-taken-place-since-the-flattened-side-marks-the-dorsum-or-back-of-the-embryo-while-the-convex-side-is-ventral-it-may-be-seen-further-that-the-blastopore-is-inclined-towards-the-dorsal-side-of-the-embryo-the-dorsal-inclination-of-the-blastopore-is-eminently-characteristic-of-the-vertebrate-yastrula-from-the-ascidians-up-to-the-high-RJ26RH.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. A ij„ii m "Si. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate yastrula from the Ascidians up to the high Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. A ij„ii m "Si. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate yastrula from the Ascidians up to the high Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-a-ijii-m-quotsi-while-the-opposite-side-is-flattened-this-is-an-indication-that-dorso-ventral-differentiation-has-taken-place-since-the-flattened-side-marks-the-dorsum-or-back-of-the-embryo-while-the-convex-side-is-ventral-it-may-be-seen-further-that-the-blastopore-is-inclined-towards-the-dorsal-side-of-the-embryo-the-dorsal-inclination-of-the-blastopore-is-eminently-characteristic-of-the-vertebrate-yastrula-from-the-ascidians-up-to-the-high-image234847861.htmlRMRJ26RH–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. A ij„ii m "Si. while the opposite side is flattened ; this is an indication that dorso-ventral differentiation has taken place, since the flattened side marks the dorsum or back of the embryo, while the convex side is ventral. It may be seen further that the blastopore is inclined towards the dorsal side of the embryo. The dorsal inclination of the blastopore is eminently characteristic of the vertebrate yastrula from the Ascidians up to the high
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. EMBRYOXIC BEVELOPMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of embryology. EMBRYONIC DEVELOrMEXT. Fertilisation and Scg'>nc!itation of the Ovum. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonadic pouches become very much distended bv the ripening of the ova and spermatozoa in the respective sexes, and finall}- burst, discharging their contents into the atrial cavit}-, whence they reach the exterior through th Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-embryoxic-bevelopmext-105-ascidians-and-of-amphioxus-marks-a-distinct-epoch-in-the-progress-of-the-science-of-embryology-embryonic-develormext-fertilisation-and-scggtnc!itation-of-the-ovum-the-breeding-season-of-amphioxus-extends-in-the-med-iterranean-from-spring-to-autumn-the-gonadic-pouches-become-very-much-distended-bv-the-ripening-of-the-ova-and-spermatozoa-in-the-respective-sexes-and-finall-burst-discharging-their-contents-into-the-atrial-cavit-whence-they-reach-the-exterior-through-th-image232347549.htmlRMRE09JN–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. EMBRYOXIC BEVELOPMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of embryology. EMBRYONIC DEVELOrMEXT. Fertilisation and Scg'>nc!itation of the Ovum. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonadic pouches become very much distended bv the ripening of the ova and spermatozoa in the respective sexes, and finall}- burst, discharging their contents into the atrial cavit}-, whence they reach the exterior through th
. A general guide to the British Museum (Natural History) ... With plans and a view of the building. British Museum (Natural History). 58 WHALE ROOM. Tunicates, or Ascidians, are worthy of the best attention of the visitor, on account of their near affinity with the Vertebrate stock, of which they may be regarded as a degenerate type. It is in the larvse that the evidence of vertebrate relationship is most conspicuous, as is well shown in fig. 31, where the striking resemblance between a Tadpole and a young Ascidian is dis- played. A fine series of very large shells and some interesting Cuttle Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-general-guide-to-the-british-museum-natural-history-with-plans-and-a-view-of-the-building-british-museum-natural-history-58-whale-room-tunicates-or-ascidians-are-worthy-of-the-best-attention-of-the-visitor-on-account-of-their-near-affinity-with-the-vertebrate-stock-of-which-they-may-be-regarded-as-a-degenerate-type-it-is-in-the-larvse-that-the-evidence-of-vertebrate-relationship-is-most-conspicuous-as-is-well-shown-in-fig-31-where-the-striking-resemblance-between-a-tadpole-and-a-young-ascidian-is-dis-played-a-fine-series-of-very-large-shells-and-some-interesting-cuttle-image232320015.htmlRMRDY2FB–. A general guide to the British Museum (Natural History) ... With plans and a view of the building. British Museum (Natural History). 58 WHALE ROOM. Tunicates, or Ascidians, are worthy of the best attention of the visitor, on account of their near affinity with the Vertebrate stock, of which they may be regarded as a degenerate type. It is in the larvse that the evidence of vertebrate relationship is most conspicuous, as is well shown in fig. 31, where the striking resemblance between a Tadpole and a young Ascidian is dis- played. A fine series of very large shells and some interesting Cuttle
. A text-book of invertebrate morphology. Invertebrates. 624 INVERTEBRATE MORPHOLOGY. deferens (vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tunicates and in justifying the term Urochorda applied to the class, it seems convenient to depart from the usual arrangement and consider the development of the simple Ascidians here, before passing on to a description of the various orders. Devdopment of the Simple Asci- dians.—For an account of the early development refere Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-text-book-of-invertebrate-morphology-invertebrates-624-invertebrate-morphology-deferens-vd-opening-into-the-atrial-cavity-near-the-opening-of-the-oviduct-on-account-of-the-larval-characters-being-more-important-than-the-adult-in-indicating-the-affinities-of-the-tunicates-and-in-justifying-the-term-urochorda-applied-to-the-class-it-seems-convenient-to-depart-from-the-usual-arrangement-and-consider-the-development-of-the-simple-ascidians-here-before-passing-on-to-a-description-of-the-various-orders-devdopment-of-the-simple-asci-diansfor-an-account-of-the-early-development-refere-image232345435.htmlRMRE06Y7–. A text-book of invertebrate morphology. Invertebrates. 624 INVERTEBRATE MORPHOLOGY. deferens (vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tunicates and in justifying the term Urochorda applied to the class, it seems convenient to depart from the usual arrangement and consider the development of the simple Ascidians here, before passing on to a description of the various orders. Devdopment of the Simple Asci- dians.—For an account of the early development refere
![. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 624 INVERTEBRATE MORPHOLOGY. -91 deferens {vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tuuicates and in justifying the term Urochorda applied to the class, it seems convenient to depart froir the usual arrangement and consider the development of tlie simple Ascidians here, before passing on to a description of the various orders. Developme Stock Photo](https://c8.alamy.com/comp/REP1Y3/a-textbook-of-invertebrate-morphology-microform-invertebrates-morphology-animals-invertbrs-morphologie-animaux-624-invertebrate-morphology-91-deferens-vd-opening-into-the-atrial-cavity-near-the-opening-of-the-oviduct-on-account-of-the-larval-characters-being-more-important-than-the-adult-in-indicating-the-affinities-of-the-tuuicates-and-in-justifying-the-term-urochorda-applied-to-the-class-it-seems-convenient-to-depart-froir-the-usual-arrangement-and-consider-the-development-of-tlie-simple-ascidians-here-before-passing-on-to-a-description-of-the-various-orders-developme-REP1Y3.jpg ". A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 624 INVERTEBRATE MORPHOLOGY. -91 deferens {vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tuuicates and in justifying the term Urochorda applied to the class, it seems convenient to depart froir the usual arrangement and consider the development of tlie simple Ascidians here, before passing on to a description of the various orders. Developme Stock Photo")
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 624 INVERTEBRATE MORPHOLOGY. -91 deferens {vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tuuicates and in justifying the term Urochorda applied to the class, it seems convenient to depart froir the usual arrangement and consider the development of tlie simple Ascidians here, before passing on to a description of the various orders. Developme Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-textbook-of-invertebrate-morphology-microform-invertebrates-morphology-animals-invertbrs-morphologie-animaux-624-invertebrate-morphology-91-deferens-vd-opening-into-the-atrial-cavity-near-the-opening-of-the-oviduct-on-account-of-the-larval-characters-being-more-important-than-the-adult-in-indicating-the-affinities-of-the-tuuicates-and-in-justifying-the-term-urochorda-applied-to-the-class-it-seems-convenient-to-depart-froir-the-usual-arrangement-and-consider-the-development-of-tlie-simple-ascidians-here-before-passing-on-to-a-description-of-the-various-orders-developme-image232824455.htmlRMREP1Y3–. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 624 INVERTEBRATE MORPHOLOGY. -91 deferens {vd), opening into the atrial cavity near the opening of the oviduct. On account of the larval characters being more important than the adult in indicating the affinities of the Tuuicates and in justifying the term Urochorda applied to the class, it seems convenient to depart froir the usual arrangement and consider the development of tlie simple Ascidians here, before passing on to a description of the various orders. Developme
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. /;.1//M' yOA'/C DE VEI.0PMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of emhryology. ! EMIiRVOMC DKVKI.OI'MENT. Fertilisation a)ui Sci^mcntation of the Ovitm. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonailic pouches become very much distended by the ripening of the ova and spermatozoa in the respective sexes, and hnally burst, cHscharging their contents Stock Photo](https://c8.alamy.com/comp/RJ2703/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-1m-yoac-de-vei0pmext-105-ascidians-and-of-amphioxus-marks-a-distinct-epoch-in-the-progress-of-the-science-of-emhryology-!-emiirvomc-dkvkioiment-fertilisation-aui-scimcntation-of-the-ovitm-the-breeding-season-of-amphioxus-extends-in-the-med-iterranean-from-spring-to-autumn-the-gonailic-pouches-become-very-much-distended-by-the-ripening-of-the-ova-and-spermatozoa-in-the-respective-sexes-and-hnally-burst-chscharging-their-contents-RJ2703.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. /;.1//M' yOA'/C DE VEI.0PMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of emhryology. ! EMIiRVOMC DKVKI.OI'MENT. Fertilisation a)ui Sci^mcntation of the Ovitm. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonailic pouches become very much distended by the ripening of the ova and spermatozoa in the respective sexes, and hnally burst, cHscharging their contents Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. /;.1//M' yOA'/C DE VEI.0PMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of emhryology. ! EMIiRVOMC DKVKI.OI'MENT. Fertilisation a)ui Sci^mcntation of the Ovitm. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonailic pouches become very much distended by the ripening of the ova and spermatozoa in the respective sexes, and hnally burst, cHscharging their contents Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-1m-yoac-de-vei0pmext-105-ascidians-and-of-amphioxus-marks-a-distinct-epoch-in-the-progress-of-the-science-of-emhryology-!-emiirvomc-dkvkioiment-fertilisation-aui-scimcntation-of-the-ovitm-the-breeding-season-of-amphioxus-extends-in-the-med-iterranean-from-spring-to-autumn-the-gonailic-pouches-become-very-much-distended-by-the-ripening-of-the-ova-and-spermatozoa-in-the-respective-sexes-and-hnally-burst-chscharging-their-contents-image234847987.htmlRMRJ2703–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. /;.1//M' yOA'/C DE VEI.0PMEXT. 105 Ascidians and of Amphioxus marks a distinct epoch in the progress of the science of emhryology. ! EMIiRVOMC DKVKI.OI'MENT. Fertilisation a)ui Sci^mcntation of the Ovitm. The breeding-season of Amphioxus extends, in the Med- iterranean, from spring to autumn. The gonailic pouches become very much distended by the ripening of the ova and spermatozoa in the respective sexes, and hnally burst, cHscharging their contents
. The animals and man; an elementary textbook of zoology and human physiology. Zoology; Physiology. THE VERTEBRATES 193 The remaining three classes include a number of strange marine forms which until recent years were considered as worms, but which are now known to be the nearest living allies of the earliest or primitive vertebrates. The rela- tionship of these forms to vertebrates is manifest, not in the appearance or structure of the adult stage, but only during embryonic or larval stages. The ascidians.—The sea-squirts, or Ascidi- ans, common on the seashore, compose one class of these pr Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-animals-and-man-an-elementary-textbook-of-zoology-and-human-physiology-zoology-physiology-the-vertebrates-193-the-remaining-three-classes-include-a-number-of-strange-marine-forms-which-until-recent-years-were-considered-as-worms-but-which-are-now-known-to-be-the-nearest-living-allies-of-the-earliest-or-primitive-vertebrates-the-rela-tionship-of-these-forms-to-vertebrates-is-manifest-not-in-the-appearance-or-structure-of-the-adult-stage-but-only-during-embryonic-or-larval-stages-the-ascidiansthe-sea-squirts-or-ascidi-ans-common-on-the-seashore-compose-one-class-of-these-pr-image232254962.htmlRMRDT3G2–. The animals and man; an elementary textbook of zoology and human physiology. Zoology; Physiology. THE VERTEBRATES 193 The remaining three classes include a number of strange marine forms which until recent years were considered as worms, but which are now known to be the nearest living allies of the earliest or primitive vertebrates. The rela- tionship of these forms to vertebrates is manifest, not in the appearance or structure of the adult stage, but only during embryonic or larval stages. The ascidians.—The sea-squirts, or Ascidi- ans, common on the seashore, compose one class of these pr
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 232 THE ASCIDIANS. formation of tongue-bars, before the perforation of the slits, has been described by Professor T. H. Morgan. From what has been said above, we conclude that the first four pairs of primary branchial stigmata of Ciona (and this probably applies equally to many species of Phallusia) represent and are derivatives of one pair of primitive, ancestral gill-slits. After a comparatively long interval, during which the intermediate stigmata, II. and III., increase in length transversely, two more s Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-232-the-ascidians-formation-of-tongue-bars-before-the-perforation-of-the-slits-has-been-described-by-professor-t-h-morgan-from-what-has-been-said-above-we-conclude-that-the-first-four-pairs-of-primary-branchial-stigmata-of-ciona-and-this-probably-applies-equally-to-many-species-of-phallusia-represent-and-are-derivatives-of-one-pair-of-primitive-ancestral-gill-slits-after-a-comparatively-long-interval-during-which-the-intermediate-stigmata-ii-and-iii-increase-in-length-transversely-two-more-s-image232351770.htmlRMRE0F1E–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 232 THE ASCIDIANS. formation of tongue-bars, before the perforation of the slits, has been described by Professor T. H. Morgan. From what has been said above, we conclude that the first four pairs of primary branchial stigmata of Ciona (and this probably applies equally to many species of Phallusia) represent and are derivatives of one pair of primitive, ancestral gill-slits. After a comparatively long interval, during which the intermediate stigmata, II. and III., increase in length transversely, two more s
. The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 255 direct offspring of the present apes ; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged pn one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'° The Amphioxus which lives in the sand in Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-doctrine-of-descent-and-darwinism-evolution-lowest-vertebrate-animals-255-direct-offspring-of-the-present-apes-neither-do-they-infer-from-these-observations-on-the-ascidian-larva-that-vertebrate-animals-are-descended-from-the-ascidians-their-accordance-much-rather-forces-us-to-assume-an-unknown-primordial-vertebrate-family-springing-from-some-branch-of-the-heterogeneous-division-of-the-annulosa-from-these-diverged-pn-one-side-the-tes-tacea-who-might-perhaps-be-called-mischanced-vertebrata-and-on-the-other-the-true-vertebrate-animals-the-amphioxus-which-lives-in-the-sand-in-image232125689.htmlRMRDJ6K5–. The doctrine of descent and Darwinism. Evolution. LOWEST VERTEBRATE ANIMALS. 255 direct offspring of the present apes ; neither do they infer from these observations on the Ascidian larva that vertebrate animals are descended from the Ascidians. Their accordance much rather forces us to assume an unknown primordial vertebrate family, springing from some branch of the heterogeneous division of the Annulosa. From these diverged pn one side the Tes- tacea, who might perhaps be called mischanced vertebrata, and on the other the true vertebrate animals.'° The Amphioxus which lives in the sand in
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. THE ASCIDIANS. the oesophageal aperture, as a low ridge, which joins the posterior extremity of the endostyle.* Visceral Anatomy. Except in its most anterior region, the dorsal border of the pharynx lies freely in the atrial chamber. On the contrary, along its ventral border, throughout the whole length of the endo- style, it is attached to the muscular mantle. In other words, the right and left halves of the atrial cavity are continuous round the dorsal side of the pharynx, but are separated from one anothe Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-the-ascidians-the-oesophageal-aperture-as-a-low-ridge-which-joins-the-posterior-extremity-of-the-endostyle-visceral-anatomy-except-in-its-most-anterior-region-the-dorsal-border-of-the-pharynx-lies-freely-in-the-atrial-chamber-on-the-contrary-along-its-ventral-border-throughout-the-whole-length-of-the-endo-style-it-is-attached-to-the-muscular-mantle-in-other-words-the-right-and-left-halves-of-the-atrial-cavity-are-continuous-round-the-dorsal-side-of-the-pharynx-but-are-separated-from-one-anothe-image232351869.htmlRMRE0F51–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. THE ASCIDIANS. the oesophageal aperture, as a low ridge, which joins the posterior extremity of the endostyle.* Visceral Anatomy. Except in its most anterior region, the dorsal border of the pharynx lies freely in the atrial chamber. On the contrary, along its ventral border, throughout the whole length of the endo- style, it is attached to the muscular mantle. In other words, the right and left halves of the atrial cavity are continuous round the dorsal side of the pharynx, but are separated from one anothe
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland. This forms a thick layer of coarse branches, covering all par Stock Photo](https://c8.alamy.com/comp/REN0MP/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-retembling-ascidieua-from-the-latter-it-differs-in-having-papillx-on-the-ban-and-in-not-having-renal-vesicle-it-is-thus-intermediate-be-tween-phauusia-and-ascidieua-the-ganglion-is-close-to-the-dorsal-tubercle-and-there-are-no-intermediate-papiluc-in-the-absence-of-renal-vesicles-it-resembles-some-phauusia-as-if-to-offset-this-lack-of-vesicles-there-is-a-very-great-development-of-what-appears-to-be-the-py-loric-gland-this-forms-a-thick-layer-of-coarse-branches-covering-all-par-REN0MP.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland. This forms a thick layer of coarse branches, covering all par Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland. This forms a thick layer of coarse branches, covering all par Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-retembling-ascidieua-from-the-latter-it-differs-in-having-papillx-on-the-ban-and-in-not-having-renal-vesicle-it-is-thus-intermediate-be-tween-phauusia-and-ascidieua-the-ganglion-is-close-to-the-dorsal-tubercle-and-there-are-no-intermediate-papiluc-in-the-absence-of-renal-vesicles-it-resembles-some-phauusia-as-if-to-offset-this-lack-of-vesicles-there-is-a-very-great-development-of-what-appears-to-be-the-py-loric-gland-this-forms-a-thick-layer-of-coarse-branches-covering-all-par-image232801542.htmlRMREN0MP–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland. This forms a thick layer of coarse branches, covering all par
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. mmm 226 THE ASCIDLWS.. f-iJ of the neuro-hypophysial tube while the latter is still in connexion with, and therefore before the atrophy of, the cerebral vesicle, thus indicating a hastening in the devel- opment as compared with Ciona. The convexity caused in the dorsal wall of the branchial sac by the pressure of the cerebral vesicle persists as the anterior portion of the dorsal lamina, and in many or most simjjlc Ascidians becomes grooved, forming t Stock Photo](https://c8.alamy.com/comp/RJ1716/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-mmm-226-the-ascidlws-f-ij-of-the-neuro-hypophysial-tube-while-the-latter-is-still-in-connexion-with-and-therefore-before-the-atrophy-of-the-cerebral-vesicle-thus-indicating-a-hastening-in-the-devel-opment-as-compared-with-ciona-the-convexity-caused-in-the-dorsal-wall-of-the-branchial-sac-by-the-pressure-of-the-cerebral-vesicle-persists-as-the-anterior-portion-of-the-dorsal-lamina-and-in-many-or-most-simjjlc-ascidians-becomes-grooved-forming-t-RJ1716.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. mmm 226 THE ASCIDLWS.. f-iJ of the neuro-hypophysial tube while the latter is still in connexion with, and therefore before the atrophy of, the cerebral vesicle, thus indicating a hastening in the devel- opment as compared with Ciona. The convexity caused in the dorsal wall of the branchial sac by the pressure of the cerebral vesicle persists as the anterior portion of the dorsal lamina, and in many or most simjjlc Ascidians becomes grooved, forming t Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. mmm 226 THE ASCIDLWS.. f-iJ of the neuro-hypophysial tube while the latter is still in connexion with, and therefore before the atrophy of, the cerebral vesicle, thus indicating a hastening in the devel- opment as compared with Ciona. The convexity caused in the dorsal wall of the branchial sac by the pressure of the cerebral vesicle persists as the anterior portion of the dorsal lamina, and in many or most simjjlc Ascidians becomes grooved, forming t Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-mmm-226-the-ascidlws-f-ij-of-the-neuro-hypophysial-tube-while-the-latter-is-still-in-connexion-with-and-therefore-before-the-atrophy-of-the-cerebral-vesicle-thus-indicating-a-hastening-in-the-devel-opment-as-compared-with-ciona-the-convexity-caused-in-the-dorsal-wall-of-the-branchial-sac-by-the-pressure-of-the-cerebral-vesicle-persists-as-the-anterior-portion-of-the-dorsal-lamina-and-in-many-or-most-simjjlc-ascidians-becomes-grooved-forming-t-image234826066.htmlRMRJ1716–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. mmm 226 THE ASCIDLWS.. f-iJ of the neuro-hypophysial tube while the latter is still in connexion with, and therefore before the atrophy of, the cerebral vesicle, thus indicating a hastening in the devel- opment as compared with Ciona. The convexity caused in the dorsal wall of the branchial sac by the pressure of the cerebral vesicle persists as the anterior portion of the dorsal lamina, and in many or most simjjlc Ascidians becomes grooved, forming t
![. The Cambridge natural history. Zoology. 64 ASCIDIANS APPENDICULARIANS two ventral apertures). The ventral heart is simple and tubular, and periodically reverses the direction of the blood-current.. Ascidiid"? MoJ guilds Cynthnds JCompoundL Ascidians Fig. 27.—Sketch of the cnief kinds of Tunicata found in the sea. This Class is divided into three Orders:—The Appendicularians, the Ascidians, and the Salpians (see Fig. 27). Order I. Larvacea (Appendicularians). Free-swimming pelagic forms, in which the posterior part of the body takes the form of a large locomotory appendage, the. Please Stock Photo](https://c8.alamy.com/comp/RDMC9Y/the-cambridge-natural-history-zoology-64-ascidians-appendicularians-two-ventral-apertures-the-ventral-heart-is-simple-and-tubular-and-periodically-reverses-the-direction-of-the-blood-current-ascidiidquot-moj-guilds-cynthnds-jcompoundl-ascidians-fig-27sketch-of-the-cnief-kinds-of-tunicata-found-in-the-sea-this-class-is-divided-into-three-ordersthe-appendicularians-the-ascidians-and-the-salpians-see-fig-27-order-i-larvacea-appendicularians-free-swimming-pelagic-forms-in-which-the-posterior-part-of-the-body-takes-the-form-of-a-large-locomotory-appendage-the-please-RDMC9Y.jpg ". The Cambridge natural history. Zoology. 64 ASCIDIANS APPENDICULARIANS two ventral apertures). The ventral heart is simple and tubular, and periodically reverses the direction of the blood-current.. Ascidiid"? MoJ guilds Cynthnds JCompoundL Ascidians Fig. 27.—Sketch of the cnief kinds of Tunicata found in the sea. This Class is divided into three Orders:—The Appendicularians, the Ascidians, and the Salpians (see Fig. 27). Order I. Larvacea (Appendicularians). Free-swimming pelagic forms, in which the posterior part of the body takes the form of a large locomotory appendage, the. Please Stock Photo")
. The Cambridge natural history. Zoology. 64 ASCIDIANS APPENDICULARIANS two ventral apertures). The ventral heart is simple and tubular, and periodically reverses the direction of the blood-current.. Ascidiid"? MoJ guilds Cynthnds JCompoundL Ascidians Fig. 27.—Sketch of the cnief kinds of Tunicata found in the sea. This Class is divided into three Orders:—The Appendicularians, the Ascidians, and the Salpians (see Fig. 27). Order I. Larvacea (Appendicularians). Free-swimming pelagic forms, in which the posterior part of the body takes the form of a large locomotory appendage, the. Please Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-64-ascidians-appendicularians-two-ventral-apertures-the-ventral-heart-is-simple-and-tubular-and-periodically-reverses-the-direction-of-the-blood-current-ascidiidquot-moj-guilds-cynthnds-jcompoundl-ascidians-fig-27sketch-of-the-cnief-kinds-of-tunicata-found-in-the-sea-this-class-is-divided-into-three-ordersthe-appendicularians-the-ascidians-and-the-salpians-see-fig-27-order-i-larvacea-appendicularians-free-swimming-pelagic-forms-in-which-the-posterior-part-of-the-body-takes-the-form-of-a-large-locomotory-appendage-the-please-image232174039.htmlRMRDMC9Y–. The Cambridge natural history. Zoology. 64 ASCIDIANS APPENDICULARIANS two ventral apertures). The ventral heart is simple and tubular, and periodically reverses the direction of the blood-current.. Ascidiid"? MoJ guilds Cynthnds JCompoundL Ascidians Fig. 27.—Sketch of the cnief kinds of Tunicata found in the sea. This Class is divided into three Orders:—The Appendicularians, the Ascidians, and the Salpians (see Fig. 27). Order I. Larvacea (Appendicularians). Free-swimming pelagic forms, in which the posterior part of the body takes the form of a large locomotory appendage, the. Please
![. The Cambridge natural history. Zoology. 6o ASCIDIANS has formed the beginning of the muscular body-wall, the con- nective tissue around the organs, and the blood; the endostyle has developed as a thick-walled groove along the ventral edge of the pharynx, which has become the branchial sac; and the peri- cardial sac and its invagination the heart have formed in the mesoblast between the endostyle and stomach. The " epicardiac tubes " grow out from the posterior end of the endostyle to join the pericardium. They play an important part 'in the formation of. Fig. 26.—Metamorphosis of a Stock Photo](https://c8.alamy.com/comp/RDMCA4/the-cambridge-natural-history-zoology-6o-ascidians-has-formed-the-beginning-of-the-muscular-body-wall-the-con-nective-tissue-around-the-organs-and-the-blood-the-endostyle-has-developed-as-a-thick-walled-groove-along-the-ventral-edge-of-the-pharynx-which-has-become-the-branchial-sac-and-the-peri-cardial-sac-and-its-invagination-the-heart-have-formed-in-the-mesoblast-between-the-endostyle-and-stomach-the-quot-epicardiac-tubes-quot-grow-out-from-the-posterior-end-of-the-endostyle-to-join-the-pericardium-they-play-an-important-part-in-the-formation-of-fig-26metamorphosis-of-a-RDMCA4.jpg ". The Cambridge natural history. Zoology. 6o ASCIDIANS has formed the beginning of the muscular body-wall, the con- nective tissue around the organs, and the blood; the endostyle has developed as a thick-walled groove along the ventral edge of the pharynx, which has become the branchial sac; and the peri- cardial sac and its invagination the heart have formed in the mesoblast between the endostyle and stomach. The " epicardiac tubes " grow out from the posterior end of the endostyle to join the pericardium. They play an important part 'in the formation of. Fig. 26.—Metamorphosis of a Stock Photo")
. The Cambridge natural history. Zoology. 6o ASCIDIANS has formed the beginning of the muscular body-wall, the con- nective tissue around the organs, and the blood; the endostyle has developed as a thick-walled groove along the ventral edge of the pharynx, which has become the branchial sac; and the peri- cardial sac and its invagination the heart have formed in the mesoblast between the endostyle and stomach. The " epicardiac tubes " grow out from the posterior end of the endostyle to join the pericardium. They play an important part 'in the formation of. Fig. 26.—Metamorphosis of a Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-6o-ascidians-has-formed-the-beginning-of-the-muscular-body-wall-the-con-nective-tissue-around-the-organs-and-the-blood-the-endostyle-has-developed-as-a-thick-walled-groove-along-the-ventral-edge-of-the-pharynx-which-has-become-the-branchial-sac-and-the-peri-cardial-sac-and-its-invagination-the-heart-have-formed-in-the-mesoblast-between-the-endostyle-and-stomach-the-quot-epicardiac-tubes-quot-grow-out-from-the-posterior-end-of-the-endostyle-to-join-the-pericardium-they-play-an-important-part-in-the-formation-of-fig-26metamorphosis-of-a-image232174044.htmlRMRDMCA4–. The Cambridge natural history. Zoology. 6o ASCIDIANS has formed the beginning of the muscular body-wall, the con- nective tissue around the organs, and the blood; the endostyle has developed as a thick-walled groove along the ventral edge of the pharynx, which has become the branchial sac; and the peri- cardial sac and its invagination the heart have formed in the mesoblast between the endostyle and stomach. The " epicardiac tubes " grow out from the posterior end of the endostyle to join the pericardium. They play an important part 'in the formation of. Fig. 26.—Metamorphosis of a
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. INTERNAL ANA TOMY. 47 of the Arthropoda (Insects and Crustacea) and the Mollusca are characterised by the possession of a definite muscular heart, yet in the various groups of worms there are many which possess a very elaborate vascular system, while not one of them possesses a heart. In fact, in the last-mentioned forms, the place of a heart is taken, func- tionally, by contractile blood-vessels. And this is the case with Amphioxus. Among the Vertebrates, including the Ascidians, it forms the unique instanc Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-internal-ana-tomy-47-of-the-arthropoda-insects-and-crustacea-and-the-mollusca-are-characterised-by-the-possession-of-a-definite-muscular-heart-yet-in-the-various-groups-of-worms-there-are-many-which-possess-a-very-elaborate-vascular-system-while-not-one-of-them-possesses-a-heart-in-fact-in-the-last-mentioned-forms-the-place-of-a-heart-is-taken-func-tionally-by-contractile-blood-vessels-and-this-is-the-case-with-amphioxus-among-the-vertebrates-including-the-ascidians-it-forms-the-unique-instanc-image232347675.htmlRMRE09R7–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. INTERNAL ANA TOMY. 47 of the Arthropoda (Insects and Crustacea) and the Mollusca are characterised by the possession of a definite muscular heart, yet in the various groups of worms there are many which possess a very elaborate vascular system, while not one of them possesses a heart. In fact, in the last-mentioned forms, the place of a heart is taken, func- tionally, by contractile blood-vessels. And this is the case with Amphioxus. Among the Vertebrates, including the Ascidians, it forms the unique instanc
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 236 THE ASCIDIANS. ance, doubles up obliquely forwards to the left atrial chamber, into which it opens by the anus (Fig. 107). In the angle made by the outgoing intestine with the stomach, a blind diverticulum arises. It is at first a sim- ple coecum, but soon begins to branch (Fig. 105 C), and finally forms an arborescent growth embracing the in- testine (Fig. 107). This is the so-called pyloric gland, and it is probably homologous with the hepatic cceciim of Amphioxus. Appendicidaria. It is generally agree Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-236-the-ascidians-ance-doubles-up-obliquely-forwards-to-the-left-atrial-chamber-into-which-it-opens-by-the-anus-fig-107-in-the-angle-made-by-the-outgoing-intestine-with-the-stomach-a-blind-diverticulum-arises-it-is-at-first-a-sim-ple-coecum-but-soon-begins-to-branch-fig-105-c-and-finally-forms-an-arborescent-growth-embracing-the-in-testine-fig-107-this-is-the-so-called-pyloric-gland-and-it-is-probably-homologous-with-the-hepatic-cceciim-of-amphioxus-appendicidaria-it-is-generally-agree-image232351759.htmlRMRE0F13–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 236 THE ASCIDIANS. ance, doubles up obliquely forwards to the left atrial chamber, into which it opens by the anus (Fig. 107). In the angle made by the outgoing intestine with the stomach, a blind diverticulum arises. It is at first a sim- ple coecum, but soon begins to branch (Fig. 105 C), and finally forms an arborescent growth embracing the in- testine (Fig. 107). This is the so-called pyloric gland, and it is probably homologous with the hepatic cceciim of Amphioxus. Appendicidaria. It is generally agree
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. ANA7'03fy AND DEVELOPMENT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitiidinalgroove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.^ The fact has already been stated above that the elonga- tion of the body proper of an Ascidian embr Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-ana703fy-and-development-211-one-feature-in-connexion-with-the-formation-of-the-atrial-cavity-in-which-the-ascidians-stand-in-marked-contrast-to-amphioxus-does-however-require-a-special-explanation-whereas-in-amphioxus-the-atrial-involution-has-the-form-of-a-longitiidinalgroove-in-the-ascidians-it-occurs-on-each-side-as-a-local-inpushing-of-the-ectoderm-with-a-minute-circular-orifice-of-invagination-the-fact-has-already-been-stated-above-that-the-elonga-tion-of-the-body-proper-of-an-ascidian-embr-image232351808.htmlRMRE0F2T–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. ANA7'03fy AND DEVELOPMENT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitiidinalgroove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.^ The fact has already been stated above that the elonga- tion of the body proper of an Ascidian embr
. Mark anniversary volume; to Edward Laurens Mark, Hersey Professor of Anatomy and Director of the Zoo?logical Laboratory at Harvard University, in celebration of twenty-five years of successful work for the advancement of zoo?logy. Mark, E. L. (Edward Laurens), 1847-1946; Zoology; Anatomy, Comparative; Physiology; Embryology. THE STRUCTURE AND AFFINITIES OF HERDMANIA CLAVIFORMIS. 257 Herdmania and its nearest relatives is its possession of two distinct epicardiac tubes. As pointed out in the description, in this character it is wholly unique among ascidians. This count alone would certainly s Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/mark-anniversary-volume-to-edward-laurens-mark-hersey-professor-of-anatomy-and-director-of-the-zoological-laboratory-at-harvard-university-in-celebration-of-twenty-five-years-of-successful-work-for-the-advancement-of-zoology-mark-e-l-edward-laurens-1847-1946-zoology-anatomy-comparative-physiology-embryology-the-structure-and-affinities-of-herdmania-claviformis-257-herdmania-and-its-nearest-relatives-is-its-possession-of-two-distinct-epicardiac-tubes-as-pointed-out-in-the-description-in-this-character-it-is-wholly-unique-among-ascidians-this-count-alone-would-certainly-s-image232147390.htmlRMRDK6A6–. Mark anniversary volume; to Edward Laurens Mark, Hersey Professor of Anatomy and Director of the Zoo?logical Laboratory at Harvard University, in celebration of twenty-five years of successful work for the advancement of zoo?logy. Mark, E. L. (Edward Laurens), 1847-1946; Zoology; Anatomy, Comparative; Physiology; Embryology. THE STRUCTURE AND AFFINITIES OF HERDMANIA CLAVIFORMIS. 257 Herdmania and its nearest relatives is its possession of two distinct epicardiac tubes. As pointed out in the description, in this character it is wholly unique among ascidians. This count alone would certainly s
![. Handbook of zoology with examples from Canadian species, recent and fossil [microform]. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE MOIJ.USCA. 110 'I'he younj;' of the Ascidians is provided with a swim- ing tail, having in it a gelatinous axis, and with a nerve fibre and muscles for locomotion. In this stage the larva resembles so closely the embryo of some fislu's that it has been considered as a link connecting the Tunicates with the X'ertebrates. It soon, however, loses the swim- ming tail, attaches itself by means of tuberc les at the opposite etremity of the sac, and become Stock Photo](https://c8.alamy.com/comp/RJ2FNA/handbook-of-zoology-with-examples-from-canadian-species-recent-and-fossil-microform-zoology-invertebrates-zoologie-invertbrs-province-moijusca-110-ihe-younj-of-the-ascidians-is-provided-with-a-swim-ing-tail-having-in-it-a-gelatinous-axis-and-with-a-nerve-fibre-and-muscles-for-locomotion-in-this-stage-the-larva-resembles-so-closely-the-embryo-of-some-fislus-that-it-has-been-considered-as-a-link-connecting-the-tunicates-with-the-xertebrates-it-soon-however-loses-the-swim-ming-tail-attaches-itself-by-means-of-tuberc-les-at-the-opposite-etremity-of-the-sac-and-become-RJ2FNA.jpg ". Handbook of zoology with examples from Canadian species, recent and fossil [microform]. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE MOIJ.USCA. 110 'I'he younj;' of the Ascidians is provided with a swim- ing tail, having in it a gelatinous axis, and with a nerve fibre and muscles for locomotion. In this stage the larva resembles so closely the embryo of some fislu's that it has been considered as a link connecting the Tunicates with the X'ertebrates. It soon, however, loses the swim- ming tail, attaches itself by means of tuberc les at the opposite etremity of the sac, and become Stock Photo")
. Handbook of zoology with examples from Canadian species, recent and fossil [microform]. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE MOIJ.USCA. 110 'I'he younj;' of the Ascidians is provided with a swim- ing tail, having in it a gelatinous axis, and with a nerve fibre and muscles for locomotion. In this stage the larva resembles so closely the embryo of some fislu's that it has been considered as a link connecting the Tunicates with the X'ertebrates. It soon, however, loses the swim- ming tail, attaches itself by means of tuberc les at the opposite etremity of the sac, and become Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/handbook-of-zoology-with-examples-from-canadian-species-recent-and-fossil-microform-zoology-invertebrates-zoologie-invertbrs-province-moijusca-110-ihe-younj-of-the-ascidians-is-provided-with-a-swim-ing-tail-having-in-it-a-gelatinous-axis-and-with-a-nerve-fibre-and-muscles-for-locomotion-in-this-stage-the-larva-resembles-so-closely-the-embryo-of-some-fislus-that-it-has-been-considered-as-a-link-connecting-the-tunicates-with-the-xertebrates-it-soon-however-loses-the-swim-ming-tail-attaches-itself-by-means-of-tuberc-les-at-the-opposite-etremity-of-the-sac-and-become-image234854854.htmlRMRJ2FNA–. Handbook of zoology with examples from Canadian species, recent and fossil [microform]. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE MOIJ.USCA. 110 'I'he younj;' of the Ascidians is provided with a swim- ing tail, having in it a gelatinous axis, and with a nerve fibre and muscles for locomotion. In this stage the larva resembles so closely the embryo of some fislu's that it has been considered as a link connecting the Tunicates with the X'ertebrates. It soon, however, loses the swim- ming tail, attaches itself by means of tuberc les at the opposite etremity of the sac, and become
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. f 114 DEVIJA)PMEXT OF AMPUIOXIS.. cavity therefore no longer opens by the blastopore to the exterior, but it communicates with tiie medullary tube. Tiie blastopore has, in fact, become converted into the ncHirnteyic canal, joining the canal of the central nervous system with the cavity of the alimentary system. This remarkable condition of things was first discovered bv KoWALi-vsKV, who also found it in the Ascidians and in a number of the higher Vert Stock Photo](https://c8.alamy.com/comp/RJ26PX/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-f-114-devijapmext-of-ampuioxis-cavity-therefore-no-longer-opens-by-the-blastopore-to-the-exterior-but-it-communicates-with-tiie-medullary-tube-tiie-blastopore-has-in-fact-become-converted-into-the-nchirnteyic-canal-joining-the-canal-of-the-central-nervous-system-with-the-cavity-of-the-alimentary-system-this-remarkable-condition-of-things-was-first-discovered-bv-kowali-vskv-who-also-found-it-in-the-ascidians-and-in-a-number-of-the-higher-vert-RJ26PX.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. f 114 DEVIJA)PMEXT OF AMPUIOXIS.. cavity therefore no longer opens by the blastopore to the exterior, but it communicates with tiie medullary tube. Tiie blastopore has, in fact, become converted into the ncHirnteyic canal, joining the canal of the central nervous system with the cavity of the alimentary system. This remarkable condition of things was first discovered bv KoWALi-vsKV, who also found it in the Ascidians and in a number of the higher Vert Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. f 114 DEVIJA)PMEXT OF AMPUIOXIS.. cavity therefore no longer opens by the blastopore to the exterior, but it communicates with tiie medullary tube. Tiie blastopore has, in fact, become converted into the ncHirnteyic canal, joining the canal of the central nervous system with the cavity of the alimentary system. This remarkable condition of things was first discovered bv KoWALi-vsKV, who also found it in the Ascidians and in a number of the higher Vert Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-f-114-devijapmext-of-ampuioxis-cavity-therefore-no-longer-opens-by-the-blastopore-to-the-exterior-but-it-communicates-with-tiie-medullary-tube-tiie-blastopore-has-in-fact-become-converted-into-the-nchirnteyic-canal-joining-the-canal-of-the-central-nervous-system-with-the-cavity-of-the-alimentary-system-this-remarkable-condition-of-things-was-first-discovered-bv-kowali-vskv-who-also-found-it-in-the-ascidians-and-in-a-number-of-the-higher-vert-image234847842.htmlRMRJ26PX–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. f 114 DEVIJA)PMEXT OF AMPUIOXIS.. cavity therefore no longer opens by the blastopore to the exterior, but it communicates with tiie medullary tube. Tiie blastopore has, in fact, become converted into the ncHirnteyic canal, joining the canal of the central nervous system with the cavity of the alimentary system. This remarkable condition of things was first discovered bv KoWALi-vsKV, who also found it in the Ascidians and in a number of the higher Vert
![. The Cambridge natural history. Zoology. ASCIDIAE COMPOSITAE—BOTRYLLIDAE, ETC. 89 many species of both these genera, which form brilliantly coloured fleshy crusts under stones and on sea-weeds at low tide. They are amongst the commonest and the most beautiful of British Ascidians. Both genera contain species remarkable for the rich profusion of ectodermal " vessels " which ramify and anastomose in the colonial test. On the margins of the colony these vessels end in knob-like dilatations, the ampullae (Fig. 46, A, tl^, which are said by Bancroft to pulsate rhythmically, and so aid in Stock Photo](https://c8.alamy.com/comp/RDMC47/the-cambridge-natural-history-zoology-ascidiae-compositaebotryllidae-etc-89-many-species-of-both-these-genera-which-form-brilliantly-coloured-fleshy-crusts-under-stones-and-on-sea-weeds-at-low-tide-they-are-amongst-the-commonest-and-the-most-beautiful-of-british-ascidians-both-genera-contain-species-remarkable-for-the-rich-profusion-of-ectodermal-quot-vessels-quot-which-ramify-and-anastomose-in-the-colonial-test-on-the-margins-of-the-colony-these-vessels-end-in-knob-like-dilatations-the-ampullae-fig-46-a-tl-which-are-said-by-bancroft-to-pulsate-rhythmically-and-so-aid-in-RDMC47.jpg ". The Cambridge natural history. Zoology. ASCIDIAE COMPOSITAE—BOTRYLLIDAE, ETC. 89 many species of both these genera, which form brilliantly coloured fleshy crusts under stones and on sea-weeds at low tide. They are amongst the commonest and the most beautiful of British Ascidians. Both genera contain species remarkable for the rich profusion of ectodermal " vessels " which ramify and anastomose in the colonial test. On the margins of the colony these vessels end in knob-like dilatations, the ampullae (Fig. 46, A, tl^, which are said by Bancroft to pulsate rhythmically, and so aid in Stock Photo")
. The Cambridge natural history. Zoology. ASCIDIAE COMPOSITAE—BOTRYLLIDAE, ETC. 89 many species of both these genera, which form brilliantly coloured fleshy crusts under stones and on sea-weeds at low tide. They are amongst the commonest and the most beautiful of British Ascidians. Both genera contain species remarkable for the rich profusion of ectodermal " vessels " which ramify and anastomose in the colonial test. On the margins of the colony these vessels end in knob-like dilatations, the ampullae (Fig. 46, A, tl^, which are said by Bancroft to pulsate rhythmically, and so aid in Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-ascidiae-compositaebotryllidae-etc-89-many-species-of-both-these-genera-which-form-brilliantly-coloured-fleshy-crusts-under-stones-and-on-sea-weeds-at-low-tide-they-are-amongst-the-commonest-and-the-most-beautiful-of-british-ascidians-both-genera-contain-species-remarkable-for-the-rich-profusion-of-ectodermal-quot-vessels-quot-which-ramify-and-anastomose-in-the-colonial-test-on-the-margins-of-the-colony-these-vessels-end-in-knob-like-dilatations-the-ampullae-fig-46-a-tl-which-are-said-by-bancroft-to-pulsate-rhythmically-and-so-aid-in-image232173879.htmlRMRDMC47–. The Cambridge natural history. Zoology. ASCIDIAE COMPOSITAE—BOTRYLLIDAE, ETC. 89 many species of both these genera, which form brilliantly coloured fleshy crusts under stones and on sea-weeds at low tide. They are amongst the commonest and the most beautiful of British Ascidians. Both genera contain species remarkable for the rich profusion of ectodermal " vessels " which ramify and anastomose in the colonial test. On the margins of the colony these vessels end in knob-like dilatations, the ampullae (Fig. 46, A, tl^, which are said by Bancroft to pulsate rhythmically, and so aid in
. Zoology : for students and general readers . Zoology. HABITS OF ASCIDIANS. 197 Balanoglossus, is a provisional one. In a diagram chowing tlie classification, i.e., the affinities of tlio different classes of animals, the Tunicates may be represented as an independent branch sent off possibly from the Trematode stem, running parallel to the worms, near Balanoglossus, and ending a little below the level of AmpJtioxus. They have certainly few niollnscan features, what do exist being superficial, and nothing to remind iis closely of the Pohjzoa or Bracliiopods, and the class is here treated of b Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-habits-of-ascidians-197-balanoglossus-is-a-provisional-one-in-a-diagram-chowing-tlie-classification-ie-the-affinities-of-tlio-different-classes-of-animals-the-tunicates-may-be-represented-as-an-independent-branch-sent-off-possibly-from-the-trematode-stem-running-parallel-to-the-worms-near-balanoglossus-and-ending-a-little-below-the-level-of-ampjtioxus-they-have-certainly-few-niollnscan-features-what-do-exist-being-superficial-and-nothing-to-remind-iis-closely-of-the-pohjzoa-or-bracliiopods-and-the-class-is-here-treated-of-b-image231938165.htmlRMRD9KDW–. Zoology : for students and general readers . Zoology. HABITS OF ASCIDIANS. 197 Balanoglossus, is a provisional one. In a diagram chowing tlie classification, i.e., the affinities of tlio different classes of animals, the Tunicates may be represented as an independent branch sent off possibly from the Trematode stem, running parallel to the worms, near Balanoglossus, and ending a little below the level of AmpJtioxus. They have certainly few niollnscan features, what do exist being superficial, and nothing to remind iis closely of the Pohjzoa or Bracliiopods, and the class is here treated of b
. Natural history. Zoology. S28 HERMICHORDA OR ENTEROPNEUSTA. marks round our shores. They are known as Ascidians or sea-squirts, and they may be either solitary or colonial. The solitary forms are sac-shaped, leathery creatures fastened at the base, and possessing a mouth at the opposite. Fig. 4.—Fykosoma. Tig. 5.—Common Sea Squikt (Aseidiella aspersa). Fig. 6.—BOTETLLUS. end. There is also another opening by which the water from the gill- slits is passed out of the body. The colonial forms are smaller in size, and are united together into irregular or star-shaped clusters usually brightly co Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/natural-history-zoology-s28-hermichorda-or-enteropneusta-marks-round-our-shores-they-are-known-as-ascidians-or-sea-squirts-and-they-may-be-either-solitary-or-colonial-the-solitary-forms-are-sac-shaped-leathery-creatures-fastened-at-the-base-and-possessing-a-mouth-at-the-opposite-fig-4fykosoma-tig-5common-sea-squikt-aseidiella-aspersa-fig-6botetllus-end-there-is-also-another-opening-by-which-the-water-from-the-gill-slits-is-passed-out-of-the-body-the-colonial-forms-are-smaller-in-size-and-are-united-together-into-irregular-or-star-shaped-clusters-usually-brightly-co-image232302459.htmlRMRDX84B–. Natural history. Zoology. S28 HERMICHORDA OR ENTEROPNEUSTA. marks round our shores. They are known as Ascidians or sea-squirts, and they may be either solitary or colonial. The solitary forms are sac-shaped, leathery creatures fastened at the base, and possessing a mouth at the opposite. Fig. 4.—Fykosoma. Tig. 5.—Common Sea Squikt (Aseidiella aspersa). Fig. 6.—BOTETLLUS. end. There is also another opening by which the water from the gill- slits is passed out of the body. The colonial forms are smaller in size, and are united together into irregular or star-shaped clusters usually brightly co
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. I9II] ASCIDIANS FROM THE COASTS OF CANADA. «4S Dorsal lamina with smooth margin, extending behind cesophageal aperture. Pharyngeal folds represented by single longitudinal bars, which are very thin and broad. Infundibula as described above. Margin of anus lobed. Only one gonad and that placed on the inner side of intestinal loop; oviduct accompanying rectum; testes peripheral, their duct or ducts not accompanying oviduct. It might be well to retain Bostrichobranchus as a subgenus, if ther Stock Photo](https://c8.alamy.com/comp/REN0MA/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-i9ii-ascidians-from-the-coasts-of-canada-4s-dorsal-lamina-with-smooth-margin-extending-behind-cesophageal-aperture-pharyngeal-folds-represented-by-single-longitudinal-bars-which-are-very-thin-and-broad-infundibula-as-described-above-margin-of-anus-lobed-only-one-gonad-and-that-placed-on-the-inner-side-of-intestinal-loop-oviduct-accompanying-rectum-testes-peripheral-their-duct-or-ducts-not-accompanying-oviduct-it-might-be-well-to-retain-bostrichobranchus-as-a-subgenus-if-ther-REN0MA.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. I9II] ASCIDIANS FROM THE COASTS OF CANADA. «4S Dorsal lamina with smooth margin, extending behind cesophageal aperture. Pharyngeal folds represented by single longitudinal bars, which are very thin and broad. Infundibula as described above. Margin of anus lobed. Only one gonad and that placed on the inner side of intestinal loop; oviduct accompanying rectum; testes peripheral, their duct or ducts not accompanying oviduct. It might be well to retain Bostrichobranchus as a subgenus, if ther Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. I9II] ASCIDIANS FROM THE COASTS OF CANADA. «4S Dorsal lamina with smooth margin, extending behind cesophageal aperture. Pharyngeal folds represented by single longitudinal bars, which are very thin and broad. Infundibula as described above. Margin of anus lobed. Only one gonad and that placed on the inner side of intestinal loop; oviduct accompanying rectum; testes peripheral, their duct or ducts not accompanying oviduct. It might be well to retain Bostrichobranchus as a subgenus, if ther Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-i9ii-ascidians-from-the-coasts-of-canada-4s-dorsal-lamina-with-smooth-margin-extending-behind-cesophageal-aperture-pharyngeal-folds-represented-by-single-longitudinal-bars-which-are-very-thin-and-broad-infundibula-as-described-above-margin-of-anus-lobed-only-one-gonad-and-that-placed-on-the-inner-side-of-intestinal-loop-oviduct-accompanying-rectum-testes-peripheral-their-duct-or-ducts-not-accompanying-oviduct-it-might-be-well-to-retain-bostrichobranchus-as-a-subgenus-if-ther-image232801530.htmlRMREN0MA–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. I9II] ASCIDIANS FROM THE COASTS OF CANADA. «4S Dorsal lamina with smooth margin, extending behind cesophageal aperture. Pharyngeal folds represented by single longitudinal bars, which are very thin and broad. Infundibula as described above. Margin of anus lobed. Only one gonad and that placed on the inner side of intestinal loop; oviduct accompanying rectum; testes peripheral, their duct or ducts not accompanying oviduct. It might be well to retain Bostrichobranchus as a subgenus, if ther
. Zoology : for students and general readers . Zoology. 308 zooLoo y. of several species of Molgula, but it has the five long decid- uous appendages observed in young Molgulm. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 2. Thaliacea.âOi the whole, we may regard this order, represented by Salpa (Fig. 140), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance off the shores of Southern New England, while the others Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-308-zooloo-y-of-several-species-of-molgula-but-it-has-the-five-long-decid-uous-appendages-observed-in-young-molgulm-among-the-compound-ascidians-botryllus-and-botrylloides-have-tailed-young-while-in-other-forms-there-is-no-metamorphosis-de-velopment-being-direct-order-2-thaliaceaoi-the-whole-we-may-regard-this-order-represented-by-salpa-fig-140-and-doliolum-as-comprising-the-more-specialized-forms-of-tunicates-salpa-is-pelagic-one-species-occurring-in-abundance-off-the-shores-of-southern-new-england-while-the-others-image231938147.htmlRMRD9KD7–. Zoology : for students and general readers . Zoology. 308 zooLoo y. of several species of Molgula, but it has the five long decid- uous appendages observed in young Molgulm. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 2. Thaliacea.âOi the whole, we may regard this order, represented by Salpa (Fig. 140), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance off the shores of Southern New England, while the others
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. â 't «9««1 ASCIDIANS FKOM THE COASTS Or CANADA. "39 #. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland Stock Photo](https://c8.alamy.com/comp/REN0MX/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-t-91-ascidians-fkom-the-coasts-or-canada-quot39-retembling-ascidieua-from-the-latter-it-differs-in-having-papillx-on-the-ban-and-in-not-having-renal-vesicle-it-is-thus-intermediate-be-tween-phauusia-and-ascidieua-the-ganglion-is-close-to-the-dorsal-tubercle-and-there-are-no-intermediate-papiluc-in-the-absence-of-renal-vesicles-it-resembles-some-phauusia-as-if-to-offset-this-lack-of-vesicles-there-is-a-very-great-development-of-what-appears-to-be-the-py-loric-gland-REN0MX.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. â 't «9««1 ASCIDIANS FKOM THE COASTS Or CANADA. "39 #. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. â 't «9««1 ASCIDIANS FKOM THE COASTS Or CANADA. "39 #. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-t-91-ascidians-fkom-the-coasts-or-canada-quot39-retembling-ascidieua-from-the-latter-it-differs-in-having-papillx-on-the-ban-and-in-not-having-renal-vesicle-it-is-thus-intermediate-be-tween-phauusia-and-ascidieua-the-ganglion-is-close-to-the-dorsal-tubercle-and-there-are-no-intermediate-papiluc-in-the-absence-of-renal-vesicles-it-resembles-some-phauusia-as-if-to-offset-this-lack-of-vesicles-there-is-a-very-great-development-of-what-appears-to-be-the-py-loric-gland-image232801546.htmlRMREN0MX–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. â 't «9««1 ASCIDIANS FKOM THE COASTS Or CANADA. "39 #. retembling AscidieUa. From the latter it differs in having papillx on the ban and in not having renal vesicle*. It is thus intermediate be- tween PhaUusia and AscidieUa. The ganglion is close to the dorsal tubercle and there are no intermediate papilUc. In the absence of renal vesicles, it resembles some PhaUusia. As if to offset this lack of vesicles, there is a very great development of what appears to be the py- loric gland
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. ANATOMY AND DEVELOPMENT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external apertures are seen in front, on the ventral surface behind the mouth. T Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-anatomy-and-development-237-larval-condition-of-the-fixed-ascidians-that-they-retain-the-tail-as-their-organ-of-locomotion-throughout-life-fig-111-the-tail-is-inserted-in-the-middle-of-the-ventral-surface-of-the-body-proper-and-is-obviously-a-mere-appendage-of-the-latter-the-mouth-is-terminal-or-sub-terminal-there-is-a-sin-gle-pair-of-branchial-stigmata-which-open-into-a-pair-of-tubular-atrial-cavities-whose-separate-external-apertures-are-seen-in-front-on-the-ventral-surface-behind-the-mouth-t-image232351753.htmlRMRE0F0W–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. ANATOMY AND DEVELOPMENT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external apertures are seen in front, on the ventral surface behind the mouth. T
![. Science from an easy chair; a second series. Science; Natural history. 288 TADPOLES OF THE SEA placed beyond doubt. Each piece of evidence multiplies enormously the chances against the resemblance being due to coincidence, and not to identity of race. So it is w;*h our tadpoles of the sea. They do not merely resemble vertebrates—they are vertebrates ; they belong to that great line of the animal pedigree. The strange immobile mollusc-like sacs known as " Ascidians " or " sea-squirts," so unlike the little tadpoles from which they grow, are. Fig. 37.—Two stages in the fixa Stock Photo](https://c8.alamy.com/comp/RDNW51/science-from-an-easy-chair-a-second-series-science-natural-history-288-tadpoles-of-the-sea-placed-beyond-doubt-each-piece-of-evidence-multiplies-enormously-the-chances-against-the-resemblance-being-due-to-coincidence-and-not-to-identity-of-race-so-it-is-wh-our-tadpoles-of-the-sea-they-do-not-merely-resemble-vertebratesthey-are-vertebrates-they-belong-to-that-great-line-of-the-animal-pedigree-the-strange-immobile-mollusc-like-sacs-known-as-quot-ascidians-quot-or-quot-sea-squirtsquot-so-unlike-the-little-tadpoles-from-which-they-grow-are-fig-37two-stages-in-the-fixa-RDNW51.jpg ". Science from an easy chair; a second series. Science; Natural history. 288 TADPOLES OF THE SEA placed beyond doubt. Each piece of evidence multiplies enormously the chances against the resemblance being due to coincidence, and not to identity of race. So it is w;*h our tadpoles of the sea. They do not merely resemble vertebrates—they are vertebrates ; they belong to that great line of the animal pedigree. The strange immobile mollusc-like sacs known as " Ascidians " or " sea-squirts," so unlike the little tadpoles from which they grow, are. Fig. 37.—Two stages in the fixa Stock Photo")
. Science from an easy chair; a second series. Science; Natural history. 288 TADPOLES OF THE SEA placed beyond doubt. Each piece of evidence multiplies enormously the chances against the resemblance being due to coincidence, and not to identity of race. So it is w;*h our tadpoles of the sea. They do not merely resemble vertebrates—they are vertebrates ; they belong to that great line of the animal pedigree. The strange immobile mollusc-like sacs known as " Ascidians " or " sea-squirts," so unlike the little tadpoles from which they grow, are. Fig. 37.—Two stages in the fixa Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/science-from-an-easy-chair-a-second-series-science-natural-history-288-tadpoles-of-the-sea-placed-beyond-doubt-each-piece-of-evidence-multiplies-enormously-the-chances-against-the-resemblance-being-due-to-coincidence-and-not-to-identity-of-race-so-it-is-wh-our-tadpoles-of-the-sea-they-do-not-merely-resemble-vertebratesthey-are-vertebrates-they-belong-to-that-great-line-of-the-animal-pedigree-the-strange-immobile-mollusc-like-sacs-known-as-quot-ascidians-quot-or-quot-sea-squirtsquot-so-unlike-the-little-tadpoles-from-which-they-grow-are-fig-37two-stages-in-the-fixa-image232206045.htmlRMRDNW51–. Science from an easy chair; a second series. Science; Natural history. 288 TADPOLES OF THE SEA placed beyond doubt. Each piece of evidence multiplies enormously the chances against the resemblance being due to coincidence, and not to identity of race. So it is w;*h our tadpoles of the sea. They do not merely resemble vertebrates—they are vertebrates ; they belong to that great line of the animal pedigree. The strange immobile mollusc-like sacs known as " Ascidians " or " sea-squirts," so unlike the little tadpoles from which they grow, are. Fig. 37.—Two stages in the fixa
. A manual of zoology. Zoology. 4:22 ARTEROrODA. Salpa), and the Notodelphid^, parasitic in the gills of ascidians, form a transition to the next order. Order II. Siphonostomata (Parasita.) There are also Copepoda to which the account in large type will not apply, animals of such strange appearance that many of them were long regarded as parasitic worms (figs. 6, 428, 425). Their mandibles are altered to piercing bristles and enclosed in a piercing proboscis formed of upper and lower lips. With this sucking organ they bore into the skin or gills of fishes. They have cylindrical forms or bodies Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-manual-of-zoology-zoology-422-arteroroda-salpa-and-the-notodelphid-parasitic-in-the-gills-of-ascidians-form-a-transition-to-the-next-order-order-ii-siphonostomata-parasita-there-are-also-copepoda-to-which-the-account-in-large-type-will-not-apply-animals-of-such-strange-appearance-that-many-of-them-were-long-regarded-as-parasitic-worms-figs-6-428-425-their-mandibles-are-altered-to-piercing-bristles-and-enclosed-in-a-piercing-proboscis-formed-of-upper-and-lower-lips-with-this-sucking-organ-they-bore-into-the-skin-or-gills-of-fishes-they-have-cylindrical-forms-or-bodies-image232346742.htmlRMRE08HX–. A manual of zoology. Zoology. 4:22 ARTEROrODA. Salpa), and the Notodelphid^, parasitic in the gills of ascidians, form a transition to the next order. Order II. Siphonostomata (Parasita.) There are also Copepoda to which the account in large type will not apply, animals of such strange appearance that many of them were long regarded as parasitic worms (figs. 6, 428, 425). Their mandibles are altered to piercing bristles and enclosed in a piercing proboscis formed of upper and lower lips. With this sucking organ they bore into the skin or gills of fishes. They have cylindrical forms or bodies
. The Cambridge natural history. Zoology. 46 ASCIDIANS Endostyle.—The mucus just referred to is produced in the long canal-shaped gland called the endostyle or hypobranchial groove, which runs along the entire ventral edge of the branchial sac (Fig. 18, end). The sides, and especially the floor of the endostyle, are richly ciliated, while there are four (or six) strongly-marked, peculiarly-shaped glandular tracts, two (or three) on each side (Fig. 20, gl) running along its length, and separated by areas of closely-packed fusiform cells with short cilia, amongst which are found some bipolar sen Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-46-ascidians-endostylethe-mucus-just-referred-to-is-produced-in-the-long-canal-shaped-gland-called-the-endostyle-or-hypobranchial-groove-which-runs-along-the-entire-ventral-edge-of-the-branchial-sac-fig-18-end-the-sides-and-especially-the-floor-of-the-endostyle-are-richly-ciliated-while-there-are-four-or-six-strongly-marked-peculiarly-shaped-glandular-tracts-two-or-three-on-each-side-fig-20-gl-running-along-its-length-and-separated-by-areas-of-closely-packed-fusiform-cells-with-short-cilia-amongst-which-are-found-some-bipolar-sen-image232154616.htmlRMRDKFG8–. The Cambridge natural history. Zoology. 46 ASCIDIANS Endostyle.—The mucus just referred to is produced in the long canal-shaped gland called the endostyle or hypobranchial groove, which runs along the entire ventral edge of the branchial sac (Fig. 18, end). The sides, and especially the floor of the endostyle, are richly ciliated, while there are four (or six) strongly-marked, peculiarly-shaped glandular tracts, two (or three) on each side (Fig. 20, gl) running along its length, and separated by areas of closely-packed fusiform cells with short cilia, amongst which are found some bipolar sen
. Science from an easy chair; a second series. Science; Natural history. THE SEA-SQUIRT'S YOUNG 283 apparent. The Ascidians, like other animals, produce eggs, which are duly fertilised, and in many cases grow without any delay into the shape and form of their parents. But—fortunately for our information in regard to a very interesting chapter of natural history—not all the kinds of Ascidians grow as directly and simply as pos- sible from the egg to the parental form. Some (and our common Ascidia mentula is among them) actually hatch from the egg as tadpoles—smaller than the full-sized tadpoles Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/science-from-an-easy-chair-a-second-series-science-natural-history-the-sea-squirts-young-283-apparent-the-ascidians-like-other-animals-produce-eggs-which-are-duly-fertilised-and-in-many-cases-grow-without-any-delay-into-the-shape-and-form-of-their-parents-butfortunately-for-our-information-in-regard-to-a-very-interesting-chapter-of-natural-historynot-all-the-kinds-of-ascidians-grow-as-directly-and-simply-as-pos-sible-from-the-egg-to-the-parental-form-some-and-our-common-ascidia-mentula-is-among-them-actually-hatch-from-the-egg-as-tadpolessmaller-than-the-full-sized-tadpoles-image232206051.htmlRMRDNW57–. Science from an easy chair; a second series. Science; Natural history. THE SEA-SQUIRT'S YOUNG 283 apparent. The Ascidians, like other animals, produce eggs, which are duly fertilised, and in many cases grow without any delay into the shape and form of their parents. But—fortunately for our information in regard to a very interesting chapter of natural history—not all the kinds of Ascidians grow as directly and simply as pos- sible from the egg to the parental form. Some (and our common Ascidia mentula is among them) actually hatch from the egg as tadpoles—smaller than the full-sized tadpoles
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 200 THE ASCIDIANS. ference between the Ascidian and Amphioxus. The mesoderm in the Ascidian embryo does not arise as a series of archenteric pouches, but is produced on each side by a solid proliferation of cells from the primitive endoderm which lines the archenteric cavity. This solid proliferation begins in the middle region of the embryo near the an- terior limit of the notochord, and extends backwards (Figs. 98 and 100). It takes place from the dorso-lateral cells of the endoderm, in a posi- tion corres Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-200-the-ascidians-ference-between-the-ascidian-and-amphioxus-the-mesoderm-in-the-ascidian-embryo-does-not-arise-as-a-series-of-archenteric-pouches-but-is-produced-on-each-side-by-a-solid-proliferation-of-cells-from-the-primitive-endoderm-which-lines-the-archenteric-cavity-this-solid-proliferation-begins-in-the-middle-region-of-the-embryo-near-the-an-terior-limit-of-the-notochord-and-extends-backwards-figs-98-and-100-it-takes-place-from-the-dorso-lateral-cells-of-the-endoderm-in-a-posi-tion-corres-image232351832.htmlRMRE0F3M–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 200 THE ASCIDIANS. ference between the Ascidian and Amphioxus. The mesoderm in the Ascidian embryo does not arise as a series of archenteric pouches, but is produced on each side by a solid proliferation of cells from the primitive endoderm which lines the archenteric cavity. This solid proliferation begins in the middle region of the embryo near the an- terior limit of the notochord, and extends backwards (Figs. 98 and 100). It takes place from the dorso-lateral cells of the endoderm, in a posi- tion corres
. A textbook in general zoology. Zoology. XVIII. UROCHORDA AND VERTEBRATA Branch XII. — Choedata (continued) Class —UEOOHORDA (with notochord) Sea Squirts Sea squirts. — The animals of this class are not well known to most of us. They are called ascidians as well as tunicates. They are marine animals, some species of which live a free-swimming life, while others are attached to rocks and are unable to move from place to place any more than the sponges. Like the sponges, many of them reproduce by bud- ding, thus forming large colonies of individuals. Other species pass a soli- tary existence. I Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-textbook-in-general-zoology-zoology-xviii-urochorda-and-vertebrata-branch-xii-choedata-continued-class-ueoohorda-with-notochord-sea-squirts-sea-squirts-the-animals-of-this-class-are-not-well-known-to-most-of-us-they-are-called-ascidians-as-well-as-tunicates-they-are-marine-animals-some-species-of-which-live-a-free-swimming-life-while-others-are-attached-to-rocks-and-are-unable-to-move-from-place-to-place-any-more-than-the-sponges-like-the-sponges-many-of-them-reproduce-by-bud-ding-thus-forming-large-colonies-of-individuals-other-species-pass-a-soli-tary-existence-i-image232113444.htmlRMRDHK1T–. A textbook in general zoology. Zoology. XVIII. UROCHORDA AND VERTEBRATA Branch XII. — Choedata (continued) Class —UEOOHORDA (with notochord) Sea Squirts Sea squirts. — The animals of this class are not well known to most of us. They are called ascidians as well as tunicates. They are marine animals, some species of which live a free-swimming life, while others are attached to rocks and are unable to move from place to place any more than the sponges. Like the sponges, many of them reproduce by bud- ding, thus forming large colonies of individuals. Other species pass a soli- tary existence. I
. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTIOK BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as MedusiB, swimming Polyps, Ascidians, and such like; quite suddenly the ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two dfiys we sailed without interruption through fields of gigantic Pyrosomata {P.gigantevm, see fig. 71), which swam so c Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-life-as-affected-by-the-natural-conditions-of-existence-animal-ecology-distkibutiok-by-cukeents-279-animal-world-was-remarkably-poor-in-species-and-more-par-ticularly-was-it-devoid-of-all-the-larger-forms-as-medusib-swimming-polyps-ascidians-and-such-like-quite-suddenly-the-ocean-teemed-with-abundant-life-as-we-entered-on-the-warm-mozambique-current-to-the-east-of-the-cape-the-whole-sea-was-literally-covered-with-animals-of-every-kind-and-for-more-than-two-dfiys-we-sailed-without-interruption-through-fields-of-gigantic-pyrosomata-pgigantevm-see-fig-71-which-swam-so-c-image232032015.htmlRMRDDY5K–. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTIOK BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as MedusiB, swimming Polyps, Ascidians, and such like; quite suddenly the ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two dfiys we sailed without interruption through fields of gigantic Pyrosomata {P.gigantevm, see fig. 71), which swam so c
. Zoology. Zoology. 138 ZOOLOGY. There are in Salpa two kinds of individuals, i.e., the solitary and the aggregated or chain Saljias. The young of many Ascidians are born with a tadpole- shape, in which there is a notocord, which, however, does not extend to the brain, and the mouth-opening is dorsal rather than ventral (Fig. 180), otherwise the larval Ascid- ian is strikingly like the embryo lamprey: in both, the. Fia. 179.—Diagram of embryo Lamprey. TIC bt e. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloratio Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-zoology-138-zoology-there-are-in-salpa-two-kinds-of-individuals-ie-the-solitary-and-the-aggregated-or-chain-saljias-the-young-of-many-ascidians-are-born-with-a-tadpole-shape-in-which-there-is-a-notocord-which-however-does-not-extend-to-the-brain-and-the-mouth-opening-is-dorsal-rather-than-ventral-fig-180-otherwise-the-larval-ascid-ian-is-strikingly-like-the-embryo-lamprey-in-both-the-fia-179diagram-of-embryo-lamprey-tic-bt-e-please-note-that-these-images-are-extracted-from-scanned-page-images-that-may-have-been-digitally-enhanced-for-readability-coloratio-image232260003.htmlRMRDTA03–. Zoology. Zoology. 138 ZOOLOGY. There are in Salpa two kinds of individuals, i.e., the solitary and the aggregated or chain Saljias. The young of many Ascidians are born with a tadpole- shape, in which there is a notocord, which, however, does not extend to the brain, and the mouth-opening is dorsal rather than ventral (Fig. 180), otherwise the larval Ascid- ian is strikingly like the embryo lamprey: in both, the. Fia. 179.—Diagram of embryo Lamprey. TIC bt e. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloratio
. The Cambridge natural history. Zoology. 52 ASCIDIANS All the blood-spaces and lacunae are probably derived, like the cavity of the heart, from the blastocoel of the embryo, and are not, like the cavity of the pericardium, a part of the coelom (of endodermal origin). Neural Gland and Dorsal Tubercle.—In the dorsal median line near the anterior end of the body, and imbedded in the mantle on the ventral ^ surface of the nerve-ganglion, there lies a small Glandular mass—the neural gland—which, as Julin first n.gl. Please note that these images are extracted from scanned page images that may have Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-52-ascidians-all-the-blood-spaces-and-lacunae-are-probably-derived-like-the-cavity-of-the-heart-from-the-blastocoel-of-the-embryo-and-are-not-like-the-cavity-of-the-pericardium-a-part-of-the-coelom-of-endodermal-origin-neural-gland-and-dorsal-tuberclein-the-dorsal-median-line-near-the-anterior-end-of-the-body-and-imbedded-in-the-mantle-on-the-ventral-surface-of-the-nerve-ganglion-there-lies-a-small-glandular-massthe-neural-glandwhich-as-julin-first-ngl-please-note-that-these-images-are-extracted-from-scanned-page-images-that-may-have-image232174063.htmlRMRDMCAR–. The Cambridge natural history. Zoology. 52 ASCIDIANS All the blood-spaces and lacunae are probably derived, like the cavity of the heart, from the blastocoel of the embryo, and are not, like the cavity of the pericardium, a part of the coelom (of endodermal origin). Neural Gland and Dorsal Tubercle.—In the dorsal median line near the anterior end of the body, and imbedded in the mantle on the ventral ^ surface of the nerve-ganglion, there lies a small Glandular mass—the neural gland—which, as Julin first n.gl. Please note that these images are extracted from scanned page images that may have
![. The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES CLAVELINIDAE 71 Sub-Order 1. Ascidiae Simplices. Fixed Ascidians, which are solitary, and very rarely reproduce by gemmation; if, as in a few cases, small colonies are formed, the members are not buried in a common investing mass, but each has a distinct test of its own. No strict line of demarcation can be drawn between the Simple and Compound Ascidians; and one of the families of the former group, the Clavelinidae (the " Social" Ascidians of Milne-Edwards), forms a transition from the typical Simple forms which never repr Stock Photo](https://c8.alamy.com/comp/RDMC8N/the-cambridge-natural-history-zoology-ascidiae-simplices-clavelinidae-71-sub-order-1-ascidiae-simplices-fixed-ascidians-which-are-solitary-and-very-rarely-reproduce-by-gemmation-if-as-in-a-few-cases-small-colonies-are-formed-the-members-are-not-buried-in-a-common-investing-mass-but-each-has-a-distinct-test-of-its-own-no-strict-line-of-demarcation-can-be-drawn-between-the-simple-and-compound-ascidians-and-one-of-the-families-of-the-former-group-the-clavelinidae-the-quot-socialquot-ascidians-of-milne-edwards-forms-a-transition-from-the-typical-simple-forms-which-never-repr-RDMC8N.jpg ". The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES CLAVELINIDAE 71 Sub-Order 1. Ascidiae Simplices. Fixed Ascidians, which are solitary, and very rarely reproduce by gemmation; if, as in a few cases, small colonies are formed, the members are not buried in a common investing mass, but each has a distinct test of its own. No strict line of demarcation can be drawn between the Simple and Compound Ascidians; and one of the families of the former group, the Clavelinidae (the " Social" Ascidians of Milne-Edwards), forms a transition from the typical Simple forms which never repr Stock Photo")
. The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES CLAVELINIDAE 71 Sub-Order 1. Ascidiae Simplices. Fixed Ascidians, which are solitary, and very rarely reproduce by gemmation; if, as in a few cases, small colonies are formed, the members are not buried in a common investing mass, but each has a distinct test of its own. No strict line of demarcation can be drawn between the Simple and Compound Ascidians; and one of the families of the former group, the Clavelinidae (the " Social" Ascidians of Milne-Edwards), forms a transition from the typical Simple forms which never repr Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-ascidiae-simplices-clavelinidae-71-sub-order-1-ascidiae-simplices-fixed-ascidians-which-are-solitary-and-very-rarely-reproduce-by-gemmation-if-as-in-a-few-cases-small-colonies-are-formed-the-members-are-not-buried-in-a-common-investing-mass-but-each-has-a-distinct-test-of-its-own-no-strict-line-of-demarcation-can-be-drawn-between-the-simple-and-compound-ascidians-and-one-of-the-families-of-the-former-group-the-clavelinidae-the-quot-socialquot-ascidians-of-milne-edwards-forms-a-transition-from-the-typical-simple-forms-which-never-repr-image232174005.htmlRMRDMC8N–. The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES CLAVELINIDAE 71 Sub-Order 1. Ascidiae Simplices. Fixed Ascidians, which are solitary, and very rarely reproduce by gemmation; if, as in a few cases, small colonies are formed, the members are not buried in a common investing mass, but each has a distinct test of its own. No strict line of demarcation can be drawn between the Simple and Compound Ascidians; and one of the families of the former group, the Clavelinidae (the " Social" Ascidians of Milne-Edwards), forms a transition from the typical Simple forms which never repr
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 202 THE ASCIDIANS. oxus, but it is merely due to the outgrowth of the tail from the body of the embryo (Fig. loi). The structures involved in the outgrowing tail are the dorsal nerve-tube, the notochord, the caudal mesoderm, which lies on each side of the notochord, and will give rise to the muscles of the tail, and finally a solid cord of endo- derm consisting of two rows of cells placed side by side =. below the notochord (Fig. 99 E). As soon as the tail begins to grow out, the neu- renteric canal becomes Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-202-the-ascidians-oxus-but-it-is-merely-due-to-the-outgrowth-of-the-tail-from-the-body-of-the-embryo-fig-loi-the-structures-involved-in-the-outgrowing-tail-are-the-dorsal-nerve-tube-the-notochord-the-caudal-mesoderm-which-lies-on-each-side-of-the-notochord-and-will-give-rise-to-the-muscles-of-the-tail-and-finally-a-solid-cord-of-endo-derm-consisting-of-two-rows-of-cells-placed-side-by-side-=-below-the-notochord-fig-99-e-as-soon-as-the-tail-begins-to-grow-out-the-neu-renteric-canal-becomes-image232351827.htmlRMRE0F3F–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 202 THE ASCIDIANS. oxus, but it is merely due to the outgrowth of the tail from the body of the embryo (Fig. loi). The structures involved in the outgrowing tail are the dorsal nerve-tube, the notochord, the caudal mesoderm, which lies on each side of the notochord, and will give rise to the muscles of the tail, and finally a solid cord of endo- derm consisting of two rows of cells placed side by side =. below the notochord (Fig. 99 E). As soon as the tail begins to grow out, the neu- renteric canal becomes
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ANA TOM V AXD DEIV. /. OPMEXT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitudinal groove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.'^ The fact has already been stated abo Stock Photo](https://c8.alamy.com/comp/RJ1723/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-ana-tom-v-axd-deiv-opmext-211-one-feature-in-connexion-with-the-formation-of-the-atrial-cavity-in-which-the-ascidians-stand-in-marked-contrast-to-amphioxus-does-however-require-a-special-explanation-whereas-in-amphioxus-the-atrial-involution-has-the-form-of-a-longitudinal-groove-in-the-ascidians-it-occurs-on-each-side-as-a-local-inpushing-of-the-ectoderm-with-a-minute-circular-orifice-of-invagination-the-fact-has-already-been-stated-abo-RJ1723.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ANA TOM V AXD DEIV. /. OPMEXT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitudinal groove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.'^ The fact has already been stated abo Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ANA TOM V AXD DEIV. /. OPMEXT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitudinal groove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.'^ The fact has already been stated abo Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-ana-tom-v-axd-deiv-opmext-211-one-feature-in-connexion-with-the-formation-of-the-atrial-cavity-in-which-the-ascidians-stand-in-marked-contrast-to-amphioxus-does-however-require-a-special-explanation-whereas-in-amphioxus-the-atrial-involution-has-the-form-of-a-longitudinal-groove-in-the-ascidians-it-occurs-on-each-side-as-a-local-inpushing-of-the-ectoderm-with-a-minute-circular-orifice-of-invagination-the-fact-has-already-been-stated-abo-image234826091.htmlRMRJ1723–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ANA TOM V AXD DEIV. /. OPMEXT. 211 One feature in connexion with the formation of the atrial cavity, in which the Ascidians stand in marked contrast to Amphioxus, does, however, require a special explanation. Whereas in Amphioxus the atrial involution has the form of a longitudinal groove, in the Ascidians it occurs on each side, as a local inpushing of the ectoderm with a minute circular orifice of invagination.'^ The fact has already been stated abo
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ' !'ll*l I 196 yy/A AsciD/.txs. In correlation with this sessile habit of existence w ; find that the Ascidians, in contrast to Amphioxus, are hermaph- rodite,— an almost universal condition among sessile orp;an- isms of every description. They arc unsegmented, the muscles not being divided up into nfyotomes ; and none of their organs (gonads, lenal organs, etc.)?re metamerically repeated, unless we regard the successive transverse rows of stigmata in Stock Photo](https://c8.alamy.com/comp/RJ1745/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-!lll-i-196-yya-ascidtxs-in-correlation-with-this-sessile-habit-of-existence-w-find-that-the-ascidians-in-contrast-to-amphioxus-are-hermaph-rodite-an-almost-universal-condition-among-sessile-orpan-isms-of-every-description-they-arc-unsegmented-the-muscles-not-being-divided-up-into-nfyotomes-and-none-of-their-organs-gonads-lenal-organs-etcre-metamerically-repeated-unless-we-regard-the-successive-transverse-rows-of-stigmata-in-RJ1745.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ' !'ll*l I 196 yy/A AsciD/.txs. In correlation with this sessile habit of existence w ; find that the Ascidians, in contrast to Amphioxus, are hermaph- rodite,— an almost universal condition among sessile orp;an- isms of every description. They arc unsegmented, the muscles not being divided up into nfyotomes ; and none of their organs (gonads, lenal organs, etc.)?re metamerically repeated, unless we regard the successive transverse rows of stigmata in Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ' !'ll*l I 196 yy/A AsciD/.txs. In correlation with this sessile habit of existence w ; find that the Ascidians, in contrast to Amphioxus, are hermaph- rodite,— an almost universal condition among sessile orp;an- isms of every description. They arc unsegmented, the muscles not being divided up into nfyotomes ; and none of their organs (gonads, lenal organs, etc.)?re metamerically repeated, unless we regard the successive transverse rows of stigmata in Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-!lll-i-196-yya-ascidtxs-in-correlation-with-this-sessile-habit-of-existence-w-find-that-the-ascidians-in-contrast-to-amphioxus-are-hermaph-rodite-an-almost-universal-condition-among-sessile-orpan-isms-of-every-description-they-arc-unsegmented-the-muscles-not-being-divided-up-into-nfyotomes-and-none-of-their-organs-gonads-lenal-organs-etcre-metamerically-repeated-unless-we-regard-the-successive-transverse-rows-of-stigmata-in-image234826149.htmlRMRJ1745–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. ' !'ll*l I 196 yy/A AsciD/.txs. In correlation with this sessile habit of existence w ; find that the Ascidians, in contrast to Amphioxus, are hermaph- rodite,— an almost universal condition among sessile orp;an- isms of every description. They arc unsegmented, the muscles not being divided up into nfyotomes ; and none of their organs (gonads, lenal organs, etc.)?re metamerically repeated, unless we regard the successive transverse rows of stigmata in
. Zoology for high schools and colleges. Zoology. 398 ZOOLOGY. of several species of Molgula, but it has the five long decid- uous appendages observed in young MolgulcB. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 3. Thaliacea.—Oil the whole, we may regard this order, represented by Salpa (Fig. 386°), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance ofE the shores of Southern New England, while the others most Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-high-schools-and-colleges-zoology-398-zoology-of-several-species-of-molgula-but-it-has-the-five-long-decid-uous-appendages-observed-in-young-molgulcb-among-the-compound-ascidians-botryllus-and-botrylloides-have-tailed-young-while-in-other-forms-there-is-no-metamorphosis-de-velopment-being-direct-order-3-thaliaceaoil-the-whole-we-may-regard-this-order-represented-by-salpa-fig-386-and-doliolum-as-comprising-the-more-specialized-forms-of-tunicates-salpa-is-pelagic-one-species-occurring-in-abundance-ofe-the-shores-of-southern-new-england-while-the-others-most-image232347490.htmlRMRE09GJ–. Zoology for high schools and colleges. Zoology. 398 ZOOLOGY. of several species of Molgula, but it has the five long decid- uous appendages observed in young MolgulcB. Among the compound Ascidians, Botryllus and Botrylloides have tailed young, while in other forms there is no metamorphosis, de- velopment being direct. Order 3. Thaliacea.—Oil the whole, we may regard this order, represented by Salpa (Fig. 386°), and Doliolum, as comprising the more specialized forms of Tunicates. Salpa is pelagic, one species occurring in abundance ofE the shores of Southern New England, while the others most
![. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. .I.V.IV'OJ/y AD DEVELOPMEXT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external aperture Stock Photo](https://c8.alamy.com/comp/RJ16YK/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-ivivojy-ad-developmext-237-larval-condition-of-the-fixed-ascidians-that-they-retain-the-tail-as-their-organ-of-locomotion-throughout-life-fig-111-the-tail-is-inserted-in-the-middle-of-the-ventral-surface-of-the-body-proper-and-is-obviously-a-mere-appendage-of-the-latter-the-mouth-is-terminal-or-sub-terminal-there-is-a-sin-gle-pair-of-branchial-stigmata-which-open-into-a-pair-of-tubular-atrial-cavities-whose-separate-external-aperture-RJ16YK.jpg ". Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. .I.V.IV'OJ/y AD DEVELOPMEXT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external aperture Stock Photo")
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. .I.V.IV'OJ/y AD DEVELOPMEXT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external aperture Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-microform-vertebrates-chordata-fishes-ascidiacea-vertbrs-cords-poissons-ascidiacs-ivivojy-ad-developmext-237-larval-condition-of-the-fixed-ascidians-that-they-retain-the-tail-as-their-organ-of-locomotion-throughout-life-fig-111-the-tail-is-inserted-in-the-middle-of-the-ventral-surface-of-the-body-proper-and-is-obviously-a-mere-appendage-of-the-latter-the-mouth-is-terminal-or-sub-terminal-there-is-a-sin-gle-pair-of-branchial-stigmata-which-open-into-a-pair-of-tubular-atrial-cavities-whose-separate-external-aperture-image234826023.htmlRMRJ16YK–. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. .I.V.IV'OJ/y AD DEVELOPMEXT. 237 larval condition of the fixed Ascidians, that they retain the tail as their organ of locomotion throughout life (Fig. 111). The tail is inserted in the middle of the ventral surface of the body proper, and is obviously a mere appendage of the latter. The mouth is terminal or sub-terminal. There is a sin- gle pair of branchial stigmata, which open into a pair of tubular atrial cavities, whose separate external aperture
. The Cambridge natural history. Zoology. 8o ASCIDIANS shoe remains small, while the horns become long and much coiled so as to constitute two prominent spirals (8, 9, 10). In other exceptional forms again the curved slit becomes straightened out, undulating (11), irregularly bent (12 and 13), elaborately folded (14 and 15), or broken up into pieces (16), so that there come to be several or even a large number (17 and 18) of minute openings in place of the original single aperture. It cannot be said that any form of dorsal tubercle is charac- teristic of any of the families or genera of Ascidi Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-8o-ascidians-shoe-remains-small-while-the-horns-become-long-and-much-coiled-so-as-to-constitute-two-prominent-spirals-8-9-10-in-other-exceptional-forms-again-the-curved-slit-becomes-straightened-out-undulating-11-irregularly-bent-12-and-13-elaborately-folded-14-and-15-or-broken-up-into-pieces-16-so-that-there-come-to-be-several-or-even-a-large-number-17-and-18-of-minute-openings-in-place-of-the-original-single-aperture-it-cannot-be-said-that-any-form-of-dorsal-tubercle-is-charac-teristic-of-any-of-the-families-or-genera-of-ascidi-image232173925.htmlRMRDMC5W–. The Cambridge natural history. Zoology. 8o ASCIDIANS shoe remains small, while the horns become long and much coiled so as to constitute two prominent spirals (8, 9, 10). In other exceptional forms again the curved slit becomes straightened out, undulating (11), irregularly bent (12 and 13), elaborately folded (14 and 15), or broken up into pieces (16), so that there come to be several or even a large number (17 and 18) of minute openings in place of the original single aperture. It cannot be said that any form of dorsal tubercle is charac- teristic of any of the families or genera of Ascidi
. The Cambridge natural history. Zoology. 92 ASCIDIANS CHAP. apertures (Fig. 57, t'). There is only a single layer of adult ascidiozooids in the wall of the Fyrosoma colony, as all the fully developed ascidiozooids are placed with their antero-posterior axes at right angles to the surface and communicate by their atrial apertures with the central cavity (Fig. 56, C). Their dorsal surfaces are turned towards the open end of the colony, and the buds are given off from their ventral edges (Fig. 57). Anatomy.—The more important points in the structure of the ascidiozooid of Fyrosoma are shown in F Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-92-ascidians-chap-apertures-fig-57-t-there-is-only-a-single-layer-of-adult-ascidiozooids-in-the-wall-of-the-fyrosoma-colony-as-all-the-fully-developed-ascidiozooids-are-placed-with-their-antero-posterior-axes-at-right-angles-to-the-surface-and-communicate-by-their-atrial-apertures-with-the-central-cavity-fig-56-c-their-dorsal-surfaces-are-turned-towards-the-open-end-of-the-colony-and-the-buds-are-given-off-from-their-ventral-edges-fig-57-anatomythe-more-important-points-in-the-structure-of-the-ascidiozooid-of-fyrosoma-are-shown-in-f-image232173855.htmlRMRDMC3B–. The Cambridge natural history. Zoology. 92 ASCIDIANS CHAP. apertures (Fig. 57, t'). There is only a single layer of adult ascidiozooids in the wall of the Fyrosoma colony, as all the fully developed ascidiozooids are placed with their antero-posterior axes at right angles to the surface and communicate by their atrial apertures with the central cavity (Fig. 56, C). Their dorsal surfaces are turned towards the open end of the colony, and the buds are given off from their ventral edges (Fig. 57). Anatomy.—The more important points in the structure of the ascidiozooid of Fyrosoma are shown in F
. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 228 THE ASCIDIANS. surface-view, but they are situated at the inner or con- cave sides of the two thiclcenings. On either side of the latter can be seen the ordinary cavity of the pharynx proceeding to- wards the oesophagus. At a later stage the openings of the two first-formed stigmata become distinctly visi- ble (Fig. 105 C). Mean- while a change of axis is taking place in the body of the young Ascidian. During the extraor- dinary change of axis which we are about to describe the probos- ciform praeoral lo Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/amphioxus-and-the-ancestry-of-the-vertebrates-amphioxus-sea-squirts-hemichordata-228-the-ascidians-surface-view-but-they-are-situated-at-the-inner-or-con-cave-sides-of-the-two-thiclcenings-on-either-side-of-the-latter-can-be-seen-the-ordinary-cavity-of-the-pharynx-proceeding-to-wards-the-oesophagus-at-a-later-stage-the-openings-of-the-two-first-formed-stigmata-become-distinctly-visi-ble-fig-105-c-mean-while-a-change-of-axis-is-taking-place-in-the-body-of-the-young-ascidian-during-the-extraor-dinary-change-of-axis-which-we-are-about-to-describe-the-probos-ciform-praeoral-lo-image232351783.htmlRMRE0F1Y–. Amphioxus and the ancestry of the vertebrates. Amphioxus; Sea squirts; Hemichordata. 228 THE ASCIDIANS. surface-view, but they are situated at the inner or con- cave sides of the two thiclcenings. On either side of the latter can be seen the ordinary cavity of the pharynx proceeding to- wards the oesophagus. At a later stage the openings of the two first-formed stigmata become distinctly visi- ble (Fig. 105 C). Mean- while a change of axis is taking place in the body of the young Ascidian. During the extraor- dinary change of axis which we are about to describe the probos- ciform praeoral lo
. The Cambridge natural history. Zoology. 78 ASCIDIANS CHAP. (genus Anurella, Lacaze-Duthiers), the embryo does not become converted into a tailed larva, the development being direct without metamorphosis (see Fig. 42, C). The embryo when hatched gradually assumes the adult structure, and never shows the features characteristic of larval Ascidians, such as the urochord and the median sense - organs. Fig. 4 2 shows an Ascidiid (A), a Cynthiid (B), and this exceptional Molgulid (C), type of larva, and three forms of Compound Ascidian larvae, the Distomatid (D), the Botryllid (E), and the Diploso Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-78-ascidians-chap-genus-anurella-lacaze-duthiers-the-embryo-does-not-become-converted-into-a-tailed-larva-the-development-being-direct-without-metamorphosis-see-fig-42-c-the-embryo-when-hatched-gradually-assumes-the-adult-structure-and-never-shows-the-features-characteristic-of-larval-ascidians-such-as-the-urochord-and-the-median-sense-organs-fig-4-2-shows-an-ascidiid-a-a-cynthiid-b-and-this-exceptional-molgulid-c-type-of-larva-and-three-forms-of-compound-ascidian-larvae-the-distomatid-d-the-botryllid-e-and-the-diploso-image232173936.htmlRMRDMC68–. The Cambridge natural history. Zoology. 78 ASCIDIANS CHAP. (genus Anurella, Lacaze-Duthiers), the embryo does not become converted into a tailed larva, the development being direct without metamorphosis (see Fig. 42, C). The embryo when hatched gradually assumes the adult structure, and never shows the features characteristic of larval Ascidians, such as the urochord and the median sense - organs. Fig. 4 2 shows an Ascidiid (A), a Cynthiid (B), and this exceptional Molgulid (C), type of larva, and three forms of Compound Ascidian larvae, the Distomatid (D), the Botryllid (E), and the Diploso
. The Cambridge natural history. Zoology. 94 ASCIDIANS CHAP.. completed its development, but having precociously given rise to the budding stolon. As the four ascidiozooids increase in size, they grow round the cyathozooid and soon encircle it (Fig. 58, B). In this con- dition the young colony leaves the body of the parent and becomes free. The cyathozooid ab- sorbs the nourishing yolk upon which it lies, and dis- tributes it to the ascidio- B zooids by means of a heart and system of vessels which I have been meanwhile formed. When the cyatho- zooid atrophies and is Fig. 58.—Development of Pyr Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-94-ascidians-chap-completed-its-development-but-having-precociously-given-rise-to-the-budding-stolon-as-the-four-ascidiozooids-increase-in-size-they-grow-round-the-cyathozooid-and-soon-encircle-it-fig-58-b-in-this-con-dition-the-young-colony-leaves-the-body-of-the-parent-and-becomes-free-the-cyathozooid-ab-sorbs-the-nourishing-yolk-upon-which-it-lies-and-dis-tributes-it-to-the-ascidio-b-zooids-by-means-of-a-heart-and-system-of-vessels-which-i-have-been-meanwhile-formed-when-the-cyatho-zooid-atrophies-and-is-fig-58development-of-pyr-image232173849.htmlRMRDMC35–. The Cambridge natural history. Zoology. 94 ASCIDIANS CHAP.. completed its development, but having precociously given rise to the budding stolon. As the four ascidiozooids increase in size, they grow round the cyathozooid and soon encircle it (Fig. 58, B). In this con- dition the young colony leaves the body of the parent and becomes free. The cyathozooid ab- sorbs the nourishing yolk upon which it lies, and dis- tributes it to the ascidio- B zooids by means of a heart and system of vessels which I have been meanwhile formed. When the cyatho- zooid atrophies and is Fig. 58.—Development of Pyr
. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTION BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as Medusa, swimming Polyps, Ascidians, and such like; quite suddenly tho ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two days we sailed without interruption through fields of gigantic Pyrosomata {P.giganteum, see fig. 71), which swam so clo Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/animal-life-as-affected-by-the-natural-conditions-of-existence-animal-ecology-distkibution-by-cukeents-279-animal-world-was-remarkably-poor-in-species-and-more-par-ticularly-was-it-devoid-of-all-the-larger-forms-as-medusa-swimming-polyps-ascidians-and-such-like-quite-suddenly-tho-ocean-teemed-with-abundant-life-as-we-entered-on-the-warm-mozambique-current-to-the-east-of-the-cape-the-whole-sea-was-literally-covered-with-animals-of-every-kind-and-for-more-than-two-days-we-sailed-without-interruption-through-fields-of-gigantic-pyrosomata-pgiganteum-see-fig-71-which-swam-so-clo-image232133591.htmlRMRDJGNB–. Animal life as affected by the natural conditions of existence. Animal ecology. DISTKIBUTION BY CUKEENTS. 279 animal world was remarkably poor in species, and more par- ticularly was it devoid of all the larger forms, as Medusa, swimming Polyps, Ascidians, and such like; quite suddenly tho ocean teemed with abundant life as we entered on the warm Mozambique current to the east of the Cape. The whole sea was literally covered with animals of every kind, and for more than two days we sailed without interruption through fields of gigantic Pyrosomata {P.giganteum, see fig. 71), which swam so clo
. The Cambridge natural history. Zoology. PODOPLEA ISOKERANDRIA 71 Echinoderms, Annelids, Molluscs, and Tunicates. Lichomolgus agilis (Fig. 38) occurs in the North Sea, Atlantic, and Mediter- ranean, on the gills of large species of the Nudibranch, Doris, while L. aliens is found in the peribranchial cavity and / V«?'* cloaca of various Ascidians. Sabel- liphilus may infect the gills of Annelids such as Sabella, and is common at Liverpool. Fam. 4. Ergasilidae. â Tkersites (Fig. 39) is parasitic on the gills of various fishes, e.ff. T. gasterostei, which is common on Gasterosteus aculeakis on Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-podoplea-isokerandria-71-echinoderms-annelids-molluscs-and-tunicates-lichomolgus-agilis-fig-38-occurs-in-the-north-sea-atlantic-and-mediter-ranean-on-the-gills-of-large-species-of-the-nudibranch-doris-while-l-aliens-is-found-in-the-peribranchial-cavity-and-v-cloaca-of-various-ascidians-sabel-liphilus-may-infect-the-gills-of-annelids-such-as-sabella-and-is-common-at-liverpool-fam-4-ergasilidae-tkersites-fig-39-is-parasitic-on-the-gills-of-various-fishes-eff-t-gasterostei-which-is-common-on-gasterosteus-aculeakis-on-image232163744.htmlRMRDKY68–. The Cambridge natural history. Zoology. PODOPLEA ISOKERANDRIA 71 Echinoderms, Annelids, Molluscs, and Tunicates. Lichomolgus agilis (Fig. 38) occurs in the North Sea, Atlantic, and Mediter- ranean, on the gills of large species of the Nudibranch, Doris, while L. aliens is found in the peribranchial cavity and / V«?'* cloaca of various Ascidians. Sabel- liphilus may infect the gills of Annelids such as Sabella, and is common at Liverpool. Fam. 4. Ergasilidae. â Tkersites (Fig. 39) is parasitic on the gills of various fishes, e.ff. T. gasterostei, which is common on Gasterosteus aculeakis on
![. The Cambridge natural history. Zoology. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which lead in from r, the branchial an Stock Photo](https://c8.alamy.com/comp/RDKFGR/the-cambridge-natural-history-zoology-3quot-tissuesboth-homogeneous-and-fibrous-with-cells-blood-sinuses-and-many-muscle-bundles-large-and-small-running-circularly-longitudinally-and-obliquely-and-interlacing-in-all-directions-fig-18-m-the-muscles-are-all-formed-of-very-long-fusiform-non-striped-fibres-the-mantle-in-some-ascidians-is-often-brilliantly-pig-mented-red-yel-low-and-opaque-white-the-coloured-cells-being-exactly-like-those-found-in-the-blood-re-the-mantle-forms-two-well-marked-siphons-or-quot-short-wide-tubes-which-lead-in-from-r-the-branchial-an-RDKFGR.jpg ". The Cambridge natural history. Zoology. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which lead in from r, the branchial an Stock Photo")
. The Cambridge natural history. Zoology. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which lead in from r, the branchial an Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-3quot-tissuesboth-homogeneous-and-fibrous-with-cells-blood-sinuses-and-many-muscle-bundles-large-and-small-running-circularly-longitudinally-and-obliquely-and-interlacing-in-all-directions-fig-18-m-the-muscles-are-all-formed-of-very-long-fusiform-non-striped-fibres-the-mantle-in-some-ascidians-is-often-brilliantly-pig-mented-red-yel-low-and-opaque-white-the-coloured-cells-being-exactly-like-those-found-in-the-blood-re-the-mantle-forms-two-well-marked-siphons-or-quot-short-wide-tubes-which-lead-in-from-r-the-branchial-an-image232154631.htmlRMRDKFGR–. The Cambridge natural history. Zoology. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which lead in from r, the branchial an
. Science from an easy chair; a second series. Science; Natural history. 278 TADPOLES , OF THE SEA The Neapolitan fishermen, unlike their northern brethren, have names for several kinds of Ascidians and for a great number of the marine creatures of no market value, which they come across in searching the shallow regions of the Bay of Naples for shell-fish. If you cut one of these Ascidians open with a pen-knife you will find that the sac is very thick and tough, though translucent. Within it you will see a coiled intestine, surrounded by reddish-coloured soft material. Careful. Fio. 3«.—A diss Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/science-from-an-easy-chair-a-second-series-science-natural-history-278-tadpoles-of-the-sea-the-neapolitan-fishermen-unlike-their-northern-brethren-have-names-for-several-kinds-of-ascidians-and-for-a-great-number-of-the-marine-creatures-of-no-market-value-which-they-come-across-in-searching-the-shallow-regions-of-the-bay-of-naples-for-shell-fish-if-you-cut-one-of-these-ascidians-open-with-a-pen-knife-you-will-find-that-the-sac-is-very-thick-and-tough-though-translucent-within-it-you-will-see-a-coiled-intestine-surrounded-by-reddish-coloured-soft-material-careful-fio-3a-diss-image232206059.htmlRMRDNW5F–. Science from an easy chair; a second series. Science; Natural history. 278 TADPOLES , OF THE SEA The Neapolitan fishermen, unlike their northern brethren, have names for several kinds of Ascidians and for a great number of the marine creatures of no market value, which they come across in searching the shallow regions of the Bay of Naples for shell-fish. If you cut one of these Ascidians open with a pen-knife you will find that the sac is very thick and tough, though translucent. Within it you will see a coiled intestine, surrounded by reddish-coloured soft material. Careful. Fio. 3«.—A diss
. Natural history of animals;. Zoology. INSECTS. 139. Fig. 246.— Tunicate. TUNICATES. These animals have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clus- ters, attached by a stem to seaweed, rocks, or floating timber. They var)' from the size of a pea to several inches in diameter. They are some- times called Ascidians, from a word which means a leather bag. Strange as it may appear they are not distantly related to the Vertebrates, as is shown by their development. ARTHROPODS, OR JOINTED ANIMALS. Arthropods have no internal skeleton; the hard parts are exter Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/natural-history-of-animals-zoology-insects-139-fig-246-tunicate-tunicates-these-animals-have-no-shell-but-are-covered-with-a-tough-tunic-or-skin-sometimes-they-grow-in-clus-ters-attached-by-a-stem-to-seaweed-rocks-or-floating-timber-they-var-from-the-size-of-a-pea-to-several-inches-in-diameter-they-are-some-times-called-ascidians-from-a-word-which-means-a-leather-bag-strange-as-it-may-appear-they-are-not-distantly-related-to-the-vertebrates-as-is-shown-by-their-development-arthropods-or-jointed-animals-arthropods-have-no-internal-skeleton-the-hard-parts-are-exter-image232131244.htmlRMRDJDNG–. Natural history of animals;. Zoology. INSECTS. 139. Fig. 246.— Tunicate. TUNICATES. These animals have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clus- ters, attached by a stem to seaweed, rocks, or floating timber. They var)' from the size of a pea to several inches in diameter. They are some- times called Ascidians, from a word which means a leather bag. Strange as it may appear they are not distantly related to the Vertebrates, as is shown by their development. ARTHROPODS, OR JOINTED ANIMALS. Arthropods have no internal skeleton; the hard parts are exter
. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF ASCIDIANS. 395 (Fig. 138, A, h); whether the primitive opening (Fjg. 386*, A, a) is closed or not, KowaleTsky says is an interesting question. According to analogy with many other animals it probably closes. The larva hatches in from forty-eight to sixty hours af- ter the beginning of segmen- tation, and is then of the form indicated by Pig. 386' (copied with some additions and omissions from Kupifer's figure, being partly diagram- matic). This anatomist dis- covered in the larva of ^s- cidia canina, which is more transparent tha Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-high-schools-and-colleges-zoology-development-of-ascidians-395-fig-138-a-h-whether-the-primitive-opening-fjg-386-a-a-is-closed-or-not-kowaletsky-says-is-an-interesting-question-according-to-analogy-with-many-other-animals-it-probably-closes-the-larva-hatches-in-from-forty-eight-to-sixty-hours-af-ter-the-beginning-of-segmen-tation-and-is-then-of-the-form-indicated-by-pig-386-copied-with-some-additions-and-omissions-from-kupifers-figure-being-partly-diagram-matic-this-anatomist-dis-covered-in-the-larva-of-s-cidia-canina-which-is-more-transparent-tha-image232347495.htmlRMRE09GR–. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF ASCIDIANS. 395 (Fig. 138, A, h); whether the primitive opening (Fjg. 386*, A, a) is closed or not, KowaleTsky says is an interesting question. According to analogy with many other animals it probably closes. The larva hatches in from forty-eight to sixty hours af- ter the beginning of segmen- tation, and is then of the form indicated by Pig. 386' (copied with some additions and omissions from Kupifer's figure, being partly diagram- matic). This anatomist dis- covered in the larva of ^s- cidia canina, which is more transparent tha
![. The Cambridge natural history. Zoology. 48 ASCIDIANS pharyngo-cloacal slits) placed close to the dorsal lamina and leading direct to the cloaca. rig. 22 shows a small part of the wall of the branchial sac, in which it may be seen that the bars containing the blood- channels are arranged in three regular series:—(1) The "trans- verse vessels " which run horizontally round the wall and open at their dorsal and ventral ends into large median longitudinally running tubes, the dorsal blood-sinus (or " dorsal aorta ") behind the dorsal lamina, and the ventral blood-sinus (or &q Stock Photo](https://c8.alamy.com/comp/RDKFFW/the-cambridge-natural-history-zoology-48-ascidians-pharyngo-cloacal-slits-placed-close-to-the-dorsal-lamina-and-leading-direct-to-the-cloaca-rig-22-shows-a-small-part-of-the-wall-of-the-branchial-sac-in-which-it-may-be-seen-that-the-bars-containing-the-blood-channels-are-arranged-in-three-regular-series1-the-quottrans-verse-vessels-quot-which-run-horizontally-round-the-wall-and-open-at-their-dorsal-and-ventral-ends-into-large-median-longitudinally-running-tubes-the-dorsal-blood-sinus-or-quot-dorsal-aorta-quot-behind-the-dorsal-lamina-and-the-ventral-blood-sinus-or-q-RDKFFW.jpg ". The Cambridge natural history. Zoology. 48 ASCIDIANS pharyngo-cloacal slits) placed close to the dorsal lamina and leading direct to the cloaca. rig. 22 shows a small part of the wall of the branchial sac, in which it may be seen that the bars containing the blood- channels are arranged in three regular series:—(1) The "trans- verse vessels " which run horizontally round the wall and open at their dorsal and ventral ends into large median longitudinally running tubes, the dorsal blood-sinus (or " dorsal aorta ") behind the dorsal lamina, and the ventral blood-sinus (or &q Stock Photo")
. The Cambridge natural history. Zoology. 48 ASCIDIANS pharyngo-cloacal slits) placed close to the dorsal lamina and leading direct to the cloaca. rig. 22 shows a small part of the wall of the branchial sac, in which it may be seen that the bars containing the blood- channels are arranged in three regular series:—(1) The "trans- verse vessels " which run horizontally round the wall and open at their dorsal and ventral ends into large median longitudinally running tubes, the dorsal blood-sinus (or " dorsal aorta ") behind the dorsal lamina, and the ventral blood-sinus (or &q Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-48-ascidians-pharyngo-cloacal-slits-placed-close-to-the-dorsal-lamina-and-leading-direct-to-the-cloaca-rig-22-shows-a-small-part-of-the-wall-of-the-branchial-sac-in-which-it-may-be-seen-that-the-bars-containing-the-blood-channels-are-arranged-in-three-regular-series1-the-quottrans-verse-vessels-quot-which-run-horizontally-round-the-wall-and-open-at-their-dorsal-and-ventral-ends-into-large-median-longitudinally-running-tubes-the-dorsal-blood-sinus-or-quot-dorsal-aorta-quot-behind-the-dorsal-lamina-and-the-ventral-blood-sinus-or-q-image232154605.htmlRMRDKFFW–. The Cambridge natural history. Zoology. 48 ASCIDIANS pharyngo-cloacal slits) placed close to the dorsal lamina and leading direct to the cloaca. rig. 22 shows a small part of the wall of the branchial sac, in which it may be seen that the bars containing the blood- channels are arranged in three regular series:—(1) The "trans- verse vessels " which run horizontally round the wall and open at their dorsal and ventral ends into large median longitudinally running tubes, the dorsal blood-sinus (or " dorsal aorta ") behind the dorsal lamina, and the ventral blood-sinus (or &q
![. The Cambridge natural history. Zoology. 86 ASCIDIANS od. this genus there may be dimorphism in the buds, some of them placed deeply in the stalk having a large amount of reserve food-matter in their ectoderm, and remaining dormant until required to regenerate the " head " or upper part of the colony when it is lost. This genus was made known by the " Challenger " expedition. The species are mostly trop- ical, or from southern seas. Fam. 2. Coelocormidae. -Colony not fixed, having a large axial cavity with a terminal aperture. Bran- chial apertures five-lobed. This include Stock Photo](https://c8.alamy.com/comp/RDMC53/the-cambridge-natural-history-zoology-86-ascidians-od-this-genus-there-may-be-dimorphism-in-the-buds-some-of-them-placed-deeply-in-the-stalk-having-a-large-amount-of-reserve-food-matter-in-their-ectoderm-and-remaining-dormant-until-required-to-regenerate-the-quot-head-quot-or-upper-part-of-the-colony-when-it-is-lost-this-genus-was-made-known-by-the-quot-challenger-quot-expedition-the-species-are-mostly-trop-ical-or-from-southern-seas-fam-2-coelocormidae-colony-not-fixed-having-a-large-axial-cavity-with-a-terminal-aperture-bran-chial-apertures-five-lobed-this-include-RDMC53.jpg ". The Cambridge natural history. Zoology. 86 ASCIDIANS od. this genus there may be dimorphism in the buds, some of them placed deeply in the stalk having a large amount of reserve food-matter in their ectoderm, and remaining dormant until required to regenerate the " head " or upper part of the colony when it is lost. This genus was made known by the " Challenger " expedition. The species are mostly trop- ical, or from southern seas. Fam. 2. Coelocormidae. -Colony not fixed, having a large axial cavity with a terminal aperture. Bran- chial apertures five-lobed. This include Stock Photo")
. The Cambridge natural history. Zoology. 86 ASCIDIANS od. this genus there may be dimorphism in the buds, some of them placed deeply in the stalk having a large amount of reserve food-matter in their ectoderm, and remaining dormant until required to regenerate the " head " or upper part of the colony when it is lost. This genus was made known by the " Challenger " expedition. The species are mostly trop- ical, or from southern seas. Fam. 2. Coelocormidae. -Colony not fixed, having a large axial cavity with a terminal aperture. Bran- chial apertures five-lobed. This include Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-86-ascidians-od-this-genus-there-may-be-dimorphism-in-the-buds-some-of-them-placed-deeply-in-the-stalk-having-a-large-amount-of-reserve-food-matter-in-their-ectoderm-and-remaining-dormant-until-required-to-regenerate-the-quot-head-quot-or-upper-part-of-the-colony-when-it-is-lost-this-genus-was-made-known-by-the-quot-challenger-quot-expedition-the-species-are-mostly-trop-ical-or-from-southern-seas-fam-2-coelocormidae-colony-not-fixed-having-a-large-axial-cavity-with-a-terminal-aperture-bran-chial-apertures-five-lobed-this-include-image232173903.htmlRMRDMC53–. The Cambridge natural history. Zoology. 86 ASCIDIANS od. this genus there may be dimorphism in the buds, some of them placed deeply in the stalk having a large amount of reserve food-matter in their ectoderm, and remaining dormant until required to regenerate the " head " or upper part of the colony when it is lost. This genus was made known by the " Challenger " expedition. The species are mostly trop- ical, or from southern seas. Fam. 2. Coelocormidae. -Colony not fixed, having a large axial cavity with a terminal aperture. Bran- chial apertures five-lobed. This include
![. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photo](https://c8.alamy.com/comp/RD9KDH/zoology-for-students-and-general-readers-zoology-development-of-asgidians-203-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perojjjiora-the-original-parent-ascidian-throws-ofe-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-RD9KDH.jpg ". Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photo")
. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-students-and-general-readers-zoology-development-of-asgidians-203-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perojjjiora-the-original-parent-ascidian-throws-ofe-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-image231938157.htmlRMRD9KDH–. Zoology : for students and general readers . Zoology. DEVELOPMENT OF ASGIDIANS. 203 Huxley, merely as a kind of stalk, from -which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and PerojjJiora the original parent Ascidian throws ofE branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians
![. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF A8CIDIAN8. 3as Huxley, merely as a kind of stalk, from which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and Perophora the original parent Aseidian throws off branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians (forming Stock Photo](https://c8.alamy.com/comp/RE09GY/zoology-for-high-schools-and-colleges-zoology-development-of-a8cidian8-3as-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perophora-the-original-parent-aseidian-throws-off-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-forming-RE09GY.jpg ". Zoology for high schools and colleges. Zoology. DEVELOPMENT OF A8CIDIAN8. 3as Huxley, merely as a kind of stalk, from which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and Perophora the original parent Aseidian throws off branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians (forming Stock Photo")
. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF A8CIDIAN8. 3as Huxley, merely as a kind of stalk, from which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and Perophora the original parent Aseidian throws off branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians (forming Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/zoology-for-high-schools-and-colleges-zoology-development-of-a8cidian8-3as-huxley-merely-as-a-kind-of-stalk-from-which-new-zooids-bud-out-and-this-process-in-his-opinion-quotleads-to-the-still-more-singular-process-of-development-in-pyrosoma-in-which-the-first-formed-embryo-attains-only-an-imperfect-develop-ment-and-disappears-after-having-given-rise-to-four-ascidio-zooidsquot-in-clavellina-and-perophora-the-original-parent-aseidian-throws-off-branches-or-stolons-from-which-develop-new-individuals-the-usual-mode-of-development-in-the-simple-and-com-pound-ascidians-forming-image232347499.htmlRMRE09GY–. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF A8CIDIAN8. 3as Huxley, merely as a kind of stalk, from which new zooids bud out, and this process, in his opinion, "leads to the still more singular process of development in Pyrosoma, in which the first formed embryo attains only an imperfect develop- ment, and disappears after having given rise to four ascidio- zooids." In Clavellina and Perophora the original parent Aseidian throws off branches or stolons from which develop new individuals. The usual mode of development in the simple and com- pound Ascidians (forming
![. Elementary text-book of zoology. AMPHIOXUS 297 break up, the tail is resorbed, and the trunk rotates through nearly 180° upon its papillae. In this way the active, sensi- tive, highly - organised " tad- pole" is reduced to a quiescent, sedentary, vegetative ascidian. In Chapter VI. it is ex- plained that ontogeny may in many cases be interpreted as a repetition of phylogeny. This principle applied to the case in hand leads us to the conclusion that the ascidians are descended from active, free-swimming, highly - organ- ised Chordata which have degenerated on the adoption of a seden Stock Photo](https://c8.alamy.com/comp/RDH02R/elementary-text-book-of-zoology-amphioxus-297-break-up-the-tail-is-resorbed-and-the-trunk-rotates-through-nearly-180-upon-its-papillae-in-this-way-the-active-sensi-tive-highly-organised-quot-tad-polequot-is-reduced-to-a-quiescent-sedentary-vegetative-ascidian-in-chapter-vi-it-is-ex-plained-that-ontogeny-may-in-many-cases-be-interpreted-as-a-repetition-of-phylogeny-this-principle-applied-to-the-case-in-hand-leads-us-to-the-conclusion-that-the-ascidians-are-descended-from-active-free-swimming-highly-organ-ised-chordata-which-have-degenerated-on-the-adoption-of-a-seden-RDH02R.jpg ". Elementary text-book of zoology. AMPHIOXUS 297 break up, the tail is resorbed, and the trunk rotates through nearly 180° upon its papillae. In this way the active, sensi- tive, highly - organised " tad- pole" is reduced to a quiescent, sedentary, vegetative ascidian. In Chapter VI. it is ex- plained that ontogeny may in many cases be interpreted as a repetition of phylogeny. This principle applied to the case in hand leads us to the conclusion that the ascidians are descended from active, free-swimming, highly - organ- ised Chordata which have degenerated on the adoption of a seden Stock Photo")
. Elementary text-book of zoology. AMPHIOXUS 297 break up, the tail is resorbed, and the trunk rotates through nearly 180° upon its papillae. In this way the active, sensi- tive, highly - organised " tad- pole" is reduced to a quiescent, sedentary, vegetative ascidian. In Chapter VI. it is ex- plained that ontogeny may in many cases be interpreted as a repetition of phylogeny. This principle applied to the case in hand leads us to the conclusion that the ascidians are descended from active, free-swimming, highly - organ- ised Chordata which have degenerated on the adoption of a seden Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/elementary-text-book-of-zoology-amphioxus-297-break-up-the-tail-is-resorbed-and-the-trunk-rotates-through-nearly-180-upon-its-papillae-in-this-way-the-active-sensi-tive-highly-organised-quot-tad-polequot-is-reduced-to-a-quiescent-sedentary-vegetative-ascidian-in-chapter-vi-it-is-ex-plained-that-ontogeny-may-in-many-cases-be-interpreted-as-a-repetition-of-phylogeny-this-principle-applied-to-the-case-in-hand-leads-us-to-the-conclusion-that-the-ascidians-are-descended-from-active-free-swimming-highly-organ-ised-chordata-which-have-degenerated-on-the-adoption-of-a-seden-image232098575.htmlRMRDH02R–. Elementary text-book of zoology. AMPHIOXUS 297 break up, the tail is resorbed, and the trunk rotates through nearly 180° upon its papillae. In this way the active, sensi- tive, highly - organised " tad- pole" is reduced to a quiescent, sedentary, vegetative ascidian. In Chapter VI. it is ex- plained that ontogeny may in many cases be interpreted as a repetition of phylogeny. This principle applied to the case in hand leads us to the conclusion that the ascidians are descended from active, free-swimming, highly - organ- ised Chordata which have degenerated on the adoption of a seden
. The Cambridge natural history. Zoology. 72 ASCIDIANS CHAP. Perophora, Wiegniann, with a short compact body and intestine alongside the branchial sac. Clavelina lepadifo7'mis and Peropliora listeri are common British species found at a few fathoms depth oiT various parts of our coast. Both occur round the south end of the Isle of Man. In autumn Clavelina accumulates reserve- material in the ectoderm cells of parts of the stolon, which remain when the rest of the colony dies away, and then form new buds in spring. Fam. 2. Ascidiidae.—Solitary fixed Ascidians, never forming colonies ; with gela Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-72-ascidians-chap-perophora-wiegniann-with-a-short-compact-body-and-intestine-alongside-the-branchial-sac-clavelina-lepadifo7mis-and-peropliora-listeri-are-common-british-species-found-at-a-few-fathoms-depth-oit-various-parts-of-our-coast-both-occur-round-the-south-end-of-the-isle-of-man-in-autumn-clavelina-accumulates-reserve-material-in-the-ectoderm-cells-of-parts-of-the-stolon-which-remain-when-the-rest-of-the-colony-dies-away-and-then-form-new-buds-in-spring-fam-2-ascidiidaesolitary-fixed-ascidians-never-forming-colonies-with-gela-image232174001.htmlRMRDMC8H–. The Cambridge natural history. Zoology. 72 ASCIDIANS CHAP. Perophora, Wiegniann, with a short compact body and intestine alongside the branchial sac. Clavelina lepadifo7'mis and Peropliora listeri are common British species found at a few fathoms depth oiT various parts of our coast. Both occur round the south end of the Isle of Man. In autumn Clavelina accumulates reserve- material in the ectoderm cells of parts of the stolon, which remain when the rest of the colony dies away, and then form new buds in spring. Fam. 2. Ascidiidae.—Solitary fixed Ascidians, never forming colonies ; with gela
. Elements of zoology, to accompany the field and laboratory study of animals. Zoology. THE ANCESTHY OF VERTEBRATES 291 greatly increases. The l^ody now shows (Fig. 27G) two open- ings; one inhalent (o), and one exhalent {at). Some species, -ARVACEA > -^ d ^ ^^. Asc d id=; Mclgulids CyntTi ds JCcmipound Ascidians Fig. 274. — A group of Tunicates shomng the attached forms (Ascidiacea) both .simple (left-hand side of picture) and compound (at right) ; the oceanic form,s (Thaliacea) that swim near the surface ; and the small tailed forms (Larvacea) that look like the larval stages of higher Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/elements-of-zoology-to-accompany-the-field-and-laboratory-study-of-animals-zoology-the-ancesthy-of-vertebrates-291-greatly-increases-the-lody-now-shows-fig-27g-two-open-ings-one-inhalent-o-and-one-exhalent-at-some-species-arvacea-gt-d-asc-d-id=-mclgulids-cyntti-ds-jccmipound-ascidians-fig-274-a-group-of-tunicates-shomng-the-attached-forms-ascidiacea-both-simple-left-hand-side-of-picture-and-compound-at-right-the-oceanic-forms-thaliacea-that-swim-near-the-surface-and-the-small-tailed-forms-larvacea-that-look-like-the-larval-stages-of-higher-image232108358.htmlRMRDHCG6–. Elements of zoology, to accompany the field and laboratory study of animals. Zoology. THE ANCESTHY OF VERTEBRATES 291 greatly increases. The l^ody now shows (Fig. 27G) two open- ings; one inhalent (o), and one exhalent {at). Some species, -ARVACEA > -^ d ^ ^^. Asc d id=; Mclgulids CyntTi ds JCcmipound Ascidians Fig. 274. — A group of Tunicates shomng the attached forms (Ascidiacea) both .simple (left-hand side of picture) and compound (at right) ; the oceanic form,s (Thaliacea) that swim near the surface ; and the small tailed forms (Larvacea) that look like the larval stages of higher
. Natural history of animals. Containing brief descriptions of the animals figured on Tenney's Natural history tablets, but complete without the tablets. Zoology. Reduced. Fig. 457. — Pholas. New England and eastward.. Fig. 458. — Tunicate. TUNICATES. These are mollusks which have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clusters, attached by a stem to sea- weed, rocks, or floating timber. They vary from the size of a pea to an inch or more in diameter. They are sometimes called Ascidians, from a word which means a leather lag.. Please note that these image Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/natural-history-of-animals-containing-brief-descriptions-of-the-animals-figured-on-tenneys-natural-history-tablets-but-complete-without-the-tablets-zoology-reduced-fig-457-pholas-new-england-and-eastward-fig-458-tunicate-tunicates-these-are-mollusks-which-have-no-shell-but-are-covered-with-a-tough-tunic-or-skin-sometimes-they-grow-in-clusters-attached-by-a-stem-to-sea-weed-rocks-or-floating-timber-they-vary-from-the-size-of-a-pea-to-an-inch-or-more-in-diameter-they-are-sometimes-called-ascidians-from-a-word-which-means-a-leather-lag-please-note-that-these-image-image232034952.htmlRMRDE2XG–. Natural history of animals. Containing brief descriptions of the animals figured on Tenney's Natural history tablets, but complete without the tablets. Zoology. Reduced. Fig. 457. — Pholas. New England and eastward.. Fig. 458. — Tunicate. TUNICATES. These are mollusks which have no shell, but are covered with a tough tunic, or skin. Sometimes they grow in clusters, attached by a stem to sea- weed, rocks, or floating timber. They vary from the size of a pea to an inch or more in diameter. They are sometimes called Ascidians, from a word which means a leather lag.. Please note that these image
![. The Cambridge natural history. Zoology. STRUCTURE BRANCHIAL SAC 47 of the branchial sac to the oesophagus, guided by a membranous fold, the dorsal lamina (Fig. 21, d.l), which is more or less ridged or corrugated, and may be armed with marginal tags or even replaced by larger processes (the " languets") in some species of Ascidians. In the living animal the lamina has its free edge curved to the right hand side in such a manner as to constitute a fairly perfect tube along which the train of food passes. Branchial Sac.—Thus we have the dorsal lamina (or the languets) along the dorsa Stock Photo](https://c8.alamy.com/comp/RDKFG2/the-cambridge-natural-history-zoology-structure-branchial-sac-47-of-the-branchial-sac-to-the-oesophagus-guided-by-a-membranous-fold-the-dorsal-lamina-fig-21-dl-which-is-more-or-less-ridged-or-corrugated-and-may-be-armed-with-marginal-tags-or-even-replaced-by-larger-processes-the-quot-languetsquot-in-some-species-of-ascidians-in-the-living-animal-the-lamina-has-its-free-edge-curved-to-the-right-hand-side-in-such-a-manner-as-to-constitute-a-fairly-perfect-tube-along-which-the-train-of-food-passes-branchial-sacthus-we-have-the-dorsal-lamina-or-the-languets-along-the-dorsa-RDKFG2.jpg ". The Cambridge natural history. Zoology. STRUCTURE BRANCHIAL SAC 47 of the branchial sac to the oesophagus, guided by a membranous fold, the dorsal lamina (Fig. 21, d.l), which is more or less ridged or corrugated, and may be armed with marginal tags or even replaced by larger processes (the " languets") in some species of Ascidians. In the living animal the lamina has its free edge curved to the right hand side in such a manner as to constitute a fairly perfect tube along which the train of food passes. Branchial Sac.—Thus we have the dorsal lamina (or the languets) along the dorsa Stock Photo")
. The Cambridge natural history. Zoology. STRUCTURE BRANCHIAL SAC 47 of the branchial sac to the oesophagus, guided by a membranous fold, the dorsal lamina (Fig. 21, d.l), which is more or less ridged or corrugated, and may be armed with marginal tags or even replaced by larger processes (the " languets") in some species of Ascidians. In the living animal the lamina has its free edge curved to the right hand side in such a manner as to constitute a fairly perfect tube along which the train of food passes. Branchial Sac.—Thus we have the dorsal lamina (or the languets) along the dorsa Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-structure-branchial-sac-47-of-the-branchial-sac-to-the-oesophagus-guided-by-a-membranous-fold-the-dorsal-lamina-fig-21-dl-which-is-more-or-less-ridged-or-corrugated-and-may-be-armed-with-marginal-tags-or-even-replaced-by-larger-processes-the-quot-languetsquot-in-some-species-of-ascidians-in-the-living-animal-the-lamina-has-its-free-edge-curved-to-the-right-hand-side-in-such-a-manner-as-to-constitute-a-fairly-perfect-tube-along-which-the-train-of-food-passes-branchial-sacthus-we-have-the-dorsal-lamina-or-the-languets-along-the-dorsa-image232154610.htmlRMRDKFG2–. The Cambridge natural history. Zoology. STRUCTURE BRANCHIAL SAC 47 of the branchial sac to the oesophagus, guided by a membranous fold, the dorsal lamina (Fig. 21, d.l), which is more or less ridged or corrugated, and may be armed with marginal tags or even replaced by larger processes (the " languets") in some species of Ascidians. In the living animal the lamina has its free edge curved to the right hand side in such a manner as to constitute a fairly perfect tube along which the train of food passes. Branchial Sac.—Thus we have the dorsal lamina (or the languets) along the dorsa
![. Studies in general physiology. Physiology; Phototropism; Geotropism; Reproduction; Irritability; Regeneration (Biology). 216 Studies in Gbneeal Physiology Hydroid, Hydra, should conduct itself, so far as known, as a strictly "polarized" animal, might render it still more probable that heteromorphosis is simply a characteristic of "colony-forming" Hydrozoa. To settle this question I made experiments upon Ciona in- testinalis, a solitary Ascidian. The Ascidians, as is well known, stand near the verte- «u. brates in the animal scale. In Fig. 54 is shown in almost natural si Stock Photo](https://c8.alamy.com/comp/RDY30K/studies-in-general-physiology-physiology-phototropism-geotropism-reproduction-irritability-regeneration-biology-216-studies-in-gbneeal-physiology-hydroid-hydra-should-conduct-itself-so-far-as-known-as-a-strictly-quotpolarizedquot-animal-might-render-it-still-more-probable-that-heteromorphosis-is-simply-a-characteristic-of-quotcolony-formingquot-hydrozoa-to-settle-this-question-i-made-experiments-upon-ciona-in-testinalis-a-solitary-ascidian-the-ascidians-as-is-well-known-stand-near-the-verte-u-brates-in-the-animal-scale-in-fig-54-is-shown-in-almost-natural-si-RDY30K.jpg ". Studies in general physiology. Physiology; Phototropism; Geotropism; Reproduction; Irritability; Regeneration (Biology). 216 Studies in Gbneeal Physiology Hydroid, Hydra, should conduct itself, so far as known, as a strictly "polarized" animal, might render it still more probable that heteromorphosis is simply a characteristic of "colony-forming" Hydrozoa. To settle this question I made experiments upon Ciona in- testinalis, a solitary Ascidian. The Ascidians, as is well known, stand near the verte- «u. brates in the animal scale. In Fig. 54 is shown in almost natural si Stock Photo")
. Studies in general physiology. Physiology; Phototropism; Geotropism; Reproduction; Irritability; Regeneration (Biology). 216 Studies in Gbneeal Physiology Hydroid, Hydra, should conduct itself, so far as known, as a strictly "polarized" animal, might render it still more probable that heteromorphosis is simply a characteristic of "colony-forming" Hydrozoa. To settle this question I made experiments upon Ciona in- testinalis, a solitary Ascidian. The Ascidians, as is well known, stand near the verte- «u. brates in the animal scale. In Fig. 54 is shown in almost natural si Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/studies-in-general-physiology-physiology-phototropism-geotropism-reproduction-irritability-regeneration-biology-216-studies-in-gbneeal-physiology-hydroid-hydra-should-conduct-itself-so-far-as-known-as-a-strictly-quotpolarizedquot-animal-might-render-it-still-more-probable-that-heteromorphosis-is-simply-a-characteristic-of-quotcolony-formingquot-hydrozoa-to-settle-this-question-i-made-experiments-upon-ciona-in-testinalis-a-solitary-ascidian-the-ascidians-as-is-well-known-stand-near-the-verte-u-brates-in-the-animal-scale-in-fig-54-is-shown-in-almost-natural-si-image232320387.htmlRMRDY30K–. Studies in general physiology. Physiology; Phototropism; Geotropism; Reproduction; Irritability; Regeneration (Biology). 216 Studies in Gbneeal Physiology Hydroid, Hydra, should conduct itself, so far as known, as a strictly "polarized" animal, might render it still more probable that heteromorphosis is simply a characteristic of "colony-forming" Hydrozoa. To settle this question I made experiments upon Ciona in- testinalis, a solitary Ascidian. The Ascidians, as is well known, stand near the verte- «u. brates in the animal scale. In Fig. 54 is shown in almost natural si
![. The Cambridge natural history. Zoology. STRUCTURE BODY-WALL, ETC. 43. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which le Stock Photo](https://c8.alamy.com/comp/RDKFH1/the-cambridge-natural-history-zoology-structure-body-wall-etc-43-3quot-tissuesboth-homogeneous-and-fibrous-with-cells-blood-sinuses-and-many-muscle-bundles-large-and-small-running-circularly-longitudinally-and-obliquely-and-interlacing-in-all-directions-fig-18-m-the-muscles-are-all-formed-of-very-long-fusiform-non-striped-fibres-the-mantle-in-some-ascidians-is-often-brilliantly-pig-mented-red-yel-low-and-opaque-white-the-coloured-cells-being-exactly-like-those-found-in-the-blood-re-the-mantle-forms-two-well-marked-siphons-or-quot-short-wide-tubes-which-le-RDKFH1.jpg ". The Cambridge natural history. Zoology. STRUCTURE BODY-WALL, ETC. 43. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which le Stock Photo")
. The Cambridge natural history. Zoology. STRUCTURE BODY-WALL, ETC. 43. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which le Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-structure-body-wall-etc-43-3quot-tissuesboth-homogeneous-and-fibrous-with-cells-blood-sinuses-and-many-muscle-bundles-large-and-small-running-circularly-longitudinally-and-obliquely-and-interlacing-in-all-directions-fig-18-m-the-muscles-are-all-formed-of-very-long-fusiform-non-striped-fibres-the-mantle-in-some-ascidians-is-often-brilliantly-pig-mented-red-yel-low-and-opaque-white-the-coloured-cells-being-exactly-like-those-found-in-the-blood-re-the-mantle-forms-two-well-marked-siphons-or-quot-short-wide-tubes-which-le-image232154637.htmlRMRDKFH1–. The Cambridge natural history. Zoology. STRUCTURE BODY-WALL, ETC. 43. 3"- tissues—both homogeneous and fibrous — with cells, blood- sinuses, and many muscle - bundles large and small running circularly, longitudinally, and obliquely, and interlacing in all directions (Fig. 18, m). The muscles are all formed of very long fusiform non-striped fibres. The mantle in some Ascidians is often brilliantly pig- mented — red, yel- low and opaque white, the coloured cells being exactly like those found in the blood. re The mantle forms two well- marked siphons or ". short wide tubes, which le
![. Outlines of zoology. Zoology. 408 UROCHORDA OR TUNIC ATA. On the other hand, the development exhibits marked alternation of generations, both solitary and colonial forms being included in one life history. In Doliolum the fertilised egg gives rise to a tailed larva, which develops into an asexual "nurse, possessing the power of budding (cf. Compound Ascidians). The ventral stolon of the nurse gives rise to a number of primitive buds, which migrate over the body until they reach a dorsal outgrowth, apparently well supplied with blood. Here they fix themselves and divide up to form three Stock Photo](https://c8.alamy.com/comp/RDNYRJ/outlines-of-zoology-zoology-408-urochorda-or-tunic-ata-on-the-other-hand-the-development-exhibits-marked-alternation-of-generations-both-solitary-and-colonial-forms-being-included-in-one-life-history-in-doliolum-the-fertilised-egg-gives-rise-to-a-tailed-larva-which-develops-into-an-asexual-quotnurse-possessing-the-power-of-budding-cf-compound-ascidians-the-ventral-stolon-of-the-nurse-gives-rise-to-a-number-of-primitive-buds-which-migrate-over-the-body-until-they-reach-a-dorsal-outgrowth-apparently-well-supplied-with-blood-here-they-fix-themselves-and-divide-up-to-form-three-RDNYRJ.jpg ". Outlines of zoology. Zoology. 408 UROCHORDA OR TUNIC ATA. On the other hand, the development exhibits marked alternation of generations, both solitary and colonial forms being included in one life history. In Doliolum the fertilised egg gives rise to a tailed larva, which develops into an asexual "nurse, possessing the power of budding (cf. Compound Ascidians). The ventral stolon of the nurse gives rise to a number of primitive buds, which migrate over the body until they reach a dorsal outgrowth, apparently well supplied with blood. Here they fix themselves and divide up to form three Stock Photo")
. Outlines of zoology. Zoology. 408 UROCHORDA OR TUNIC ATA. On the other hand, the development exhibits marked alternation of generations, both solitary and colonial forms being included in one life history. In Doliolum the fertilised egg gives rise to a tailed larva, which develops into an asexual "nurse, possessing the power of budding (cf. Compound Ascidians). The ventral stolon of the nurse gives rise to a number of primitive buds, which migrate over the body until they reach a dorsal outgrowth, apparently well supplied with blood. Here they fix themselves and divide up to form three Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/outlines-of-zoology-zoology-408-urochorda-or-tunic-ata-on-the-other-hand-the-development-exhibits-marked-alternation-of-generations-both-solitary-and-colonial-forms-being-included-in-one-life-history-in-doliolum-the-fertilised-egg-gives-rise-to-a-tailed-larva-which-develops-into-an-asexual-quotnurse-possessing-the-power-of-budding-cf-compound-ascidians-the-ventral-stolon-of-the-nurse-gives-rise-to-a-number-of-primitive-buds-which-migrate-over-the-body-until-they-reach-a-dorsal-outgrowth-apparently-well-supplied-with-blood-here-they-fix-themselves-and-divide-up-to-form-three-image232208134.htmlRMRDNYRJ–. Outlines of zoology. Zoology. 408 UROCHORDA OR TUNIC ATA. On the other hand, the development exhibits marked alternation of generations, both solitary and colonial forms being included in one life history. In Doliolum the fertilised egg gives rise to a tailed larva, which develops into an asexual "nurse, possessing the power of budding (cf. Compound Ascidians). The ventral stolon of the nurse gives rise to a number of primitive buds, which migrate over the body until they reach a dorsal outgrowth, apparently well supplied with blood. Here they fix themselves and divide up to form three
![. The Cambridge natural history. Zoology. ASCIDIANS only Compound Ascidian known from a depth of 1000 fathoms; Polyclinum, Savigny, with a smooth-walled stomach (Fig. 52, A): Aplidium, Savigny, with the stomach-wall longitudinally folded (Fig. 52, B); Moixhellium, Giard, with an "areolated" stomach (Fig. 52, D), bearing knobs ou the outside ; and Amarou- ciuni, Milne-Edwards, in which the ascidiozooid has a long post- abdomen and a large atrial languet, and where the stomach-wall shows longitudinal ridges breaking up into knobs (pseudo-. FiG. 52.—Various conditions of stomach in Poly Stock Photo](https://c8.alamy.com/comp/RDMC4B/the-cambridge-natural-history-zoology-ascidians-only-compound-ascidian-known-from-a-depth-of-1000-fathoms-polyclinum-savigny-with-a-smooth-walled-stomach-fig-52-a-aplidium-savigny-with-the-stomach-wall-longitudinally-folded-fig-52-b-moixhellium-giard-with-an-quotareolatedquot-stomach-fig-52-d-bearing-knobs-ou-the-outside-and-amarou-ciuni-milne-edwards-in-which-the-ascidiozooid-has-a-long-post-abdomen-and-a-large-atrial-languet-and-where-the-stomach-wall-shows-longitudinal-ridges-breaking-up-into-knobs-pseudo-fig-52various-conditions-of-stomach-in-poly-RDMC4B.jpg ". The Cambridge natural history. Zoology. ASCIDIANS only Compound Ascidian known from a depth of 1000 fathoms; Polyclinum, Savigny, with a smooth-walled stomach (Fig. 52, A): Aplidium, Savigny, with the stomach-wall longitudinally folded (Fig. 52, B); Moixhellium, Giard, with an "areolated" stomach (Fig. 52, D), bearing knobs ou the outside ; and Amarou- ciuni, Milne-Edwards, in which the ascidiozooid has a long post- abdomen and a large atrial languet, and where the stomach-wall shows longitudinal ridges breaking up into knobs (pseudo-. FiG. 52.—Various conditions of stomach in Poly Stock Photo")
. The Cambridge natural history. Zoology. ASCIDIANS only Compound Ascidian known from a depth of 1000 fathoms; Polyclinum, Savigny, with a smooth-walled stomach (Fig. 52, A): Aplidium, Savigny, with the stomach-wall longitudinally folded (Fig. 52, B); Moixhellium, Giard, with an "areolated" stomach (Fig. 52, D), bearing knobs ou the outside ; and Amarou- ciuni, Milne-Edwards, in which the ascidiozooid has a long post- abdomen and a large atrial languet, and where the stomach-wall shows longitudinal ridges breaking up into knobs (pseudo-. FiG. 52.—Various conditions of stomach in Poly Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-ascidians-only-compound-ascidian-known-from-a-depth-of-1000-fathoms-polyclinum-savigny-with-a-smooth-walled-stomach-fig-52-a-aplidium-savigny-with-the-stomach-wall-longitudinally-folded-fig-52-b-moixhellium-giard-with-an-quotareolatedquot-stomach-fig-52-d-bearing-knobs-ou-the-outside-and-amarou-ciuni-milne-edwards-in-which-the-ascidiozooid-has-a-long-post-abdomen-and-a-large-atrial-languet-and-where-the-stomach-wall-shows-longitudinal-ridges-breaking-up-into-knobs-pseudo-fig-52various-conditions-of-stomach-in-poly-image232173883.htmlRMRDMC4B–. The Cambridge natural history. Zoology. ASCIDIANS only Compound Ascidian known from a depth of 1000 fathoms; Polyclinum, Savigny, with a smooth-walled stomach (Fig. 52, A): Aplidium, Savigny, with the stomach-wall longitudinally folded (Fig. 52, B); Moixhellium, Giard, with an "areolated" stomach (Fig. 52, D), bearing knobs ou the outside ; and Amarou- ciuni, Milne-Edwards, in which the ascidiozooid has a long post- abdomen and a large atrial languet, and where the stomach-wall shows longitudinal ridges breaking up into knobs (pseudo-. FiG. 52.—Various conditions of stomach in Poly
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one ind Stock Photo](https://c8.alamy.com/comp/REN0PK/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-ii-h-iv-igti-ii6-transactions-of-the-canadian-institute-vol-ix-at-some-distance-from-the-atrial-siphon-where-the-current-is-not-as-great-and-as-a-result-the-eggs-are-usually-retained-this-retention-of-the-eggs-may-be-quite-constant-in-a-genus-may-be-characteristic-of-certain-species-only-of-a-genus-or-may-occur-only-in-occasional-individuals-of-a-species-in-some-cases-the-eggs-are-though-retained-laid-in-lots-so-that-practically-only-one-stage-can-be-obtained-from-one-ind-REN0PK.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one ind Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one ind Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-ii-h-iv-igti-ii6-transactions-of-the-canadian-institute-vol-ix-at-some-distance-from-the-atrial-siphon-where-the-current-is-not-as-great-and-as-a-result-the-eggs-are-usually-retained-this-retention-of-the-eggs-may-be-quite-constant-in-a-genus-may-be-characteristic-of-certain-species-only-of-a-genus-or-may-occur-only-in-occasional-individuals-of-a-species-in-some-cases-the-eggs-are-though-retained-laid-in-lots-so-that-practically-only-one-stage-can-be-obtained-from-one-ind-image232801595.htmlRMREN0PK–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one ind
. The Cambridge natural history. Zoology. 74 ASCIDIANS little or no food-yolk, and the tailed larvae (Figs. 26, 42, A) are of the typical form and structure descrihed in Chapter II. Fam. 3. Cynthiidae.—Solitary fixed Ascidians (Fig. 39), sometimes occurring in aggregations, but never forming colonies; usually with leathery or fibrous, opaque test, which is sometimes encrusted with sand; branchial and atrial apertures usually both four-lobed. Branchial sac longitudinally folded (Fig. 36, A); tentacles simple or compound (Fig. 37); stigmata straight. Br.f.7. B. -end-. Please note that these imag Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-74-ascidians-little-or-no-food-yolk-and-the-tailed-larvae-figs-26-42-a-are-of-the-typical-form-and-structure-descrihed-in-chapter-ii-fam-3-cynthiidaesolitary-fixed-ascidians-fig-39-sometimes-occurring-in-aggregations-but-never-forming-colonies-usually-with-leathery-or-fibrous-opaque-test-which-is-sometimes-encrusted-with-sand-branchial-and-atrial-apertures-usually-both-four-lobed-branchial-sac-longitudinally-folded-fig-36-a-tentacles-simple-or-compound-fig-37-stigmata-straight-brf7-b-end-please-note-that-these-imag-image232173989.htmlRMRDMC85–. The Cambridge natural history. Zoology. 74 ASCIDIANS little or no food-yolk, and the tailed larvae (Figs. 26, 42, A) are of the typical form and structure descrihed in Chapter II. Fam. 3. Cynthiidae.—Solitary fixed Ascidians (Fig. 39), sometimes occurring in aggregations, but never forming colonies; usually with leathery or fibrous, opaque test, which is sometimes encrusted with sand; branchial and atrial apertures usually both four-lobed. Branchial sac longitudinally folded (Fig. 36, A); tentacles simple or compound (Fig. 37); stigmata straight. Br.f.7. B. -end-. Please note that these imag
![. The Cambridge natural history. Zoology. 70 ASCIDIANS CHAP. frequent round the British coasts, our commonest species being probably 0. dioica, Fol, and F. furcata, Moss. Young specimens appear in the plankton about February and March, and larger forms are as a rule found later in the summer. Several instances have been recorded of swarms of especially large forms, provided Ivood. bcctl Fig. 32.—Diagram oi Fritillaria seen from the right side to show the elongated body, the hood, and the relative positions of anus, atrial opening, and gonads. (Compare "with Oiko2}leura, Fig. 30.) ci. Anus Stock Photo](https://c8.alamy.com/comp/RDMC92/the-cambridge-natural-history-zoology-70-ascidians-chap-frequent-round-the-british-coasts-our-commonest-species-being-probably-0-dioica-fol-and-f-furcata-moss-young-specimens-appear-in-the-plankton-about-february-and-march-and-larger-forms-are-as-a-rule-found-later-in-the-summer-several-instances-have-been-recorded-of-swarms-of-especially-large-forms-provided-ivood-bcctl-fig-32diagram-oi-fritillaria-seen-from-the-right-side-to-show-the-elongated-body-the-hood-and-the-relative-positions-of-anus-atrial-opening-and-gonads-compare-quotwith-oiko2leura-fig-30-ci-anus-RDMC92.jpg ". The Cambridge natural history. Zoology. 70 ASCIDIANS CHAP. frequent round the British coasts, our commonest species being probably 0. dioica, Fol, and F. furcata, Moss. Young specimens appear in the plankton about February and March, and larger forms are as a rule found later in the summer. Several instances have been recorded of swarms of especially large forms, provided Ivood. bcctl Fig. 32.—Diagram oi Fritillaria seen from the right side to show the elongated body, the hood, and the relative positions of anus, atrial opening, and gonads. (Compare "with Oiko2}leura, Fig. 30.) ci. Anus Stock Photo")
. The Cambridge natural history. Zoology. 70 ASCIDIANS CHAP. frequent round the British coasts, our commonest species being probably 0. dioica, Fol, and F. furcata, Moss. Young specimens appear in the plankton about February and March, and larger forms are as a rule found later in the summer. Several instances have been recorded of swarms of especially large forms, provided Ivood. bcctl Fig. 32.—Diagram oi Fritillaria seen from the right side to show the elongated body, the hood, and the relative positions of anus, atrial opening, and gonads. (Compare "with Oiko2}leura, Fig. 30.) ci. Anus Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-70-ascidians-chap-frequent-round-the-british-coasts-our-commonest-species-being-probably-0-dioica-fol-and-f-furcata-moss-young-specimens-appear-in-the-plankton-about-february-and-march-and-larger-forms-are-as-a-rule-found-later-in-the-summer-several-instances-have-been-recorded-of-swarms-of-especially-large-forms-provided-ivood-bcctl-fig-32diagram-oi-fritillaria-seen-from-the-right-side-to-show-the-elongated-body-the-hood-and-the-relative-positions-of-anus-atrial-opening-and-gonads-compare-quotwith-oiko2leura-fig-30-ci-anus-image232174014.htmlRMRDMC92–. The Cambridge natural history. Zoology. 70 ASCIDIANS CHAP. frequent round the British coasts, our commonest species being probably 0. dioica, Fol, and F. furcata, Moss. Young specimens appear in the plankton about February and March, and larger forms are as a rule found later in the summer. Several instances have been recorded of swarms of especially large forms, provided Ivood. bcctl Fig. 32.—Diagram oi Fritillaria seen from the right side to show the elongated body, the hood, and the relative positions of anus, atrial opening, and gonads. (Compare "with Oiko2}leura, Fig. 30.) ci. Anus
. The Cambridge natural history. Zoology. FlQ. 40.—Three simple Ascidians with vascular adhering processes from the test (nat. size). A, Ascididla aspersa, 0. F. Miiller; B, Ciona intestinalis, Linn. ; C, Molgula oculata, Forb. branched hair-like processes from the test (Fig. 40, C). Branchial sac longitudinally folded; stigmata more or less curved, usually arranged in spirals (Fig. 41); tentacles compound. The chief. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-flq-40three-simple-ascidians-with-vascular-adhering-processes-from-the-test-nat-size-a-ascididla-aspersa-0-f-miiller-b-ciona-intestinalis-linn-c-molgula-oculata-forb-branched-hair-like-processes-from-the-test-fig-40-c-branchial-sac-longitudinally-folded-stigmata-more-or-less-curved-usually-arranged-in-spirals-fig-41-tentacles-compound-the-chief-please-note-that-these-images-are-extracted-from-scanned-page-images-that-may-have-been-digitally-enhanced-for-readability-coloration-and-appearance-of-these-illustrations-may-image232173950.htmlRMRDMC6P–. The Cambridge natural history. Zoology. FlQ. 40.—Three simple Ascidians with vascular adhering processes from the test (nat. size). A, Ascididla aspersa, 0. F. Miiller; B, Ciona intestinalis, Linn. ; C, Molgula oculata, Forb. branched hair-like processes from the test (Fig. 40, C). Branchial sac longitudinally folded; stigmata more or less curved, usually arranged in spirals (Fig. 41); tentacles compound. The chief. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may
![. The Cambridge natural history. Zoology. 76 ASCIDIANS " Challenger" expedition; eight or nine species are now known from various parts of the world, ranging in depth from 630 to 2425 fathoms. Most of the species are from the Pacific; only one from the North Atlantic. The curiously curved type of spicule found in the branchial sac and other organs is shown at Fig. 50, C (p. 87). Amongst the Cynthiidae are found most varied conditions of the reproductive organs. The gonads are sometimes on both, some- times on only one side of the body, sometimes in one or several. Fig. 39.—Various Cy Stock Photo](https://c8.alamy.com/comp/RDMC72/the-cambridge-natural-history-zoology-76-ascidians-quot-challengerquot-expedition-eight-or-nine-species-are-now-known-from-various-parts-of-the-world-ranging-in-depth-from-630-to-2425-fathoms-most-of-the-species-are-from-the-pacific-only-one-from-the-north-atlantic-the-curiously-curved-type-of-spicule-found-in-the-branchial-sac-and-other-organs-is-shown-at-fig-50-c-p-87-amongst-the-cynthiidae-are-found-most-varied-conditions-of-the-reproductive-organs-the-gonads-are-sometimes-on-both-some-times-on-only-one-side-of-the-body-sometimes-in-one-or-several-fig-39various-cy-RDMC72.jpg ". The Cambridge natural history. Zoology. 76 ASCIDIANS " Challenger" expedition; eight or nine species are now known from various parts of the world, ranging in depth from 630 to 2425 fathoms. Most of the species are from the Pacific; only one from the North Atlantic. The curiously curved type of spicule found in the branchial sac and other organs is shown at Fig. 50, C (p. 87). Amongst the Cynthiidae are found most varied conditions of the reproductive organs. The gonads are sometimes on both, some- times on only one side of the body, sometimes in one or several. Fig. 39.—Various Cy Stock Photo")
. The Cambridge natural history. Zoology. 76 ASCIDIANS " Challenger" expedition; eight or nine species are now known from various parts of the world, ranging in depth from 630 to 2425 fathoms. Most of the species are from the Pacific; only one from the North Atlantic. The curiously curved type of spicule found in the branchial sac and other organs is shown at Fig. 50, C (p. 87). Amongst the Cynthiidae are found most varied conditions of the reproductive organs. The gonads are sometimes on both, some- times on only one side of the body, sometimes in one or several. Fig. 39.—Various Cy Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-76-ascidians-quot-challengerquot-expedition-eight-or-nine-species-are-now-known-from-various-parts-of-the-world-ranging-in-depth-from-630-to-2425-fathoms-most-of-the-species-are-from-the-pacific-only-one-from-the-north-atlantic-the-curiously-curved-type-of-spicule-found-in-the-branchial-sac-and-other-organs-is-shown-at-fig-50-c-p-87-amongst-the-cynthiidae-are-found-most-varied-conditions-of-the-reproductive-organs-the-gonads-are-sometimes-on-both-some-times-on-only-one-side-of-the-body-sometimes-in-one-or-several-fig-39various-cy-image232173958.htmlRMRDMC72–. The Cambridge natural history. Zoology. 76 ASCIDIANS " Challenger" expedition; eight or nine species are now known from various parts of the world, ranging in depth from 630 to 2425 fathoms. Most of the species are from the Pacific; only one from the North Atlantic. The curiously curved type of spicule found in the branchial sac and other organs is shown at Fig. 50, C (p. 87). Amongst the Cynthiidae are found most varied conditions of the reproductive organs. The gonads are sometimes on both, some- times on only one side of the body, sometimes in one or several. Fig. 39.—Various Cy
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] ASCIDIANS FROM THE COASTS OF CjMKDA. tag About IS gastric folds. Apparently about is atrial tentacles. Up to 10 or II tentacles grouped at anterior end beneath pharynx. A row of testes on each side posteriorly and ventrally. In the right row there are from 6 to la and in the left from 3 to 3. They are imbedded in the test. Several colonies were obtained on the beach at Hope Island, by Rev. Mr. Taylor in 1906. This form is doubtfully distinct from M. dura Ritter from Santa Barbara, C Stock Photo](https://c8.alamy.com/comp/REN0N6/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-1911-ascidians-from-the-coasts-of-cjmkda-tag-about-is-gastric-folds-apparently-about-is-atrial-tentacles-up-to-10-or-ii-tentacles-grouped-at-anterior-end-beneath-pharynx-a-row-of-testes-on-each-side-posteriorly-and-ventrally-in-the-right-row-there-are-from-6-to-la-and-in-the-left-from-3-to-3-they-are-imbedded-in-the-test-several-colonies-were-obtained-on-the-beach-at-hope-island-by-rev-mr-taylor-in-1906-this-form-is-doubtfully-distinct-from-m-dura-ritter-from-santa-barbara-c-REN0N6.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] ASCIDIANS FROM THE COASTS OF CjMKDA. tag About IS gastric folds. Apparently about is atrial tentacles. Up to 10 or II tentacles grouped at anterior end beneath pharynx. A row of testes on each side posteriorly and ventrally. In the right row there are from 6 to la and in the left from 3 to 3. They are imbedded in the test. Several colonies were obtained on the beach at Hope Island, by Rev. Mr. Taylor in 1906. This form is doubtfully distinct from M. dura Ritter from Santa Barbara, C Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] ASCIDIANS FROM THE COASTS OF CjMKDA. tag About IS gastric folds. Apparently about is atrial tentacles. Up to 10 or II tentacles grouped at anterior end beneath pharynx. A row of testes on each side posteriorly and ventrally. In the right row there are from 6 to la and in the left from 3 to 3. They are imbedded in the test. Several colonies were obtained on the beach at Hope Island, by Rev. Mr. Taylor in 1906. This form is doubtfully distinct from M. dura Ritter from Santa Barbara, C Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-1911-ascidians-from-the-coasts-of-cjmkda-tag-about-is-gastric-folds-apparently-about-is-atrial-tentacles-up-to-10-or-ii-tentacles-grouped-at-anterior-end-beneath-pharynx-a-row-of-testes-on-each-side-posteriorly-and-ventrally-in-the-right-row-there-are-from-6-to-la-and-in-the-left-from-3-to-3-they-are-imbedded-in-the-test-several-colonies-were-obtained-on-the-beach-at-hope-island-by-rev-mr-taylor-in-1906-this-form-is-doubtfully-distinct-from-m-dura-ritter-from-santa-barbara-c-image232801554.htmlRMREN0N6–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] ASCIDIANS FROM THE COASTS OF CjMKDA. tag About IS gastric folds. Apparently about is atrial tentacles. Up to 10 or II tentacles grouped at anterior end beneath pharynx. A row of testes on each side posteriorly and ventrally. In the right row there are from 6 to la and in the left from 3 to 3. They are imbedded in the test. Several colonies were obtained on the beach at Hope Island, by Rev. Mr. Taylor in 1906. This form is doubtfully distinct from M. dura Ritter from Santa Barbara, C
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 19"] ASCIDIANS FROM THE COASTS OF CaNAOA. «3S Genus, Tetkyum {sens, hoc.) Syn. Cynthia, Hatocyntkia, Pyura auct. part., non Tetkyum Hart- meyer, 1909. Oral aperture terminal, atrial on dorsal side. Siphonal spinules acicular. Surface with simple or branched spines. Aperture of dorsal tubercle curved, usually forming two cone-shaped coils; opening between horns directed forwards and to left. Dorsal groove with languets. Number of folds variable, increasing with age, at least 6, the se Stock Photo](https://c8.alamy.com/comp/REN0N3/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-19quot-ascidians-from-the-coasts-of-canaoa-3s-genus-tetkyum-sens-hoc-syn-cynthia-hatocyntkia-pyura-auct-part-non-tetkyum-hart-meyer-1909-oral-aperture-terminal-atrial-on-dorsal-side-siphonal-spinules-acicular-surface-with-simple-or-branched-spines-aperture-of-dorsal-tubercle-curved-usually-forming-two-cone-shaped-coils-opening-between-horns-directed-forwards-and-to-left-dorsal-groove-with-languets-number-of-folds-variable-increasing-with-age-at-least-6-the-se-REN0N3.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 19"] ASCIDIANS FROM THE COASTS OF CaNAOA. «3S Genus, Tetkyum {sens, hoc.) Syn. Cynthia, Hatocyntkia, Pyura auct. part., non Tetkyum Hart- meyer, 1909. Oral aperture terminal, atrial on dorsal side. Siphonal spinules acicular. Surface with simple or branched spines. Aperture of dorsal tubercle curved, usually forming two cone-shaped coils; opening between horns directed forwards and to left. Dorsal groove with languets. Number of folds variable, increasing with age, at least 6, the se Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 19"] ASCIDIANS FROM THE COASTS OF CaNAOA. «3S Genus, Tetkyum {sens, hoc.) Syn. Cynthia, Hatocyntkia, Pyura auct. part., non Tetkyum Hart- meyer, 1909. Oral aperture terminal, atrial on dorsal side. Siphonal spinules acicular. Surface with simple or branched spines. Aperture of dorsal tubercle curved, usually forming two cone-shaped coils; opening between horns directed forwards and to left. Dorsal groove with languets. Number of folds variable, increasing with age, at least 6, the se Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-19quot-ascidians-from-the-coasts-of-canaoa-3s-genus-tetkyum-sens-hoc-syn-cynthia-hatocyntkia-pyura-auct-part-non-tetkyum-hart-meyer-1909-oral-aperture-terminal-atrial-on-dorsal-side-siphonal-spinules-acicular-surface-with-simple-or-branched-spines-aperture-of-dorsal-tubercle-curved-usually-forming-two-cone-shaped-coils-opening-between-horns-directed-forwards-and-to-left-dorsal-groove-with-languets-number-of-folds-variable-increasing-with-age-at-least-6-the-se-image232801551.htmlRMREN0N3–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 19"] ASCIDIANS FROM THE COASTS OF CaNAOA. «3S Genus, Tetkyum {sens, hoc.) Syn. Cynthia, Hatocyntkia, Pyura auct. part., non Tetkyum Hart- meyer, 1909. Oral aperture terminal, atrial on dorsal side. Siphonal spinules acicular. Surface with simple or branched spines. Aperture of dorsal tubercle curved, usually forming two cone-shaped coils; opening between horns directed forwards and to left. Dorsal groove with languets. Number of folds variable, increasing with age, at least 6, the se
. The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES ASCIDIIDAE 73 present (Fig. 15, p. 40); Bhodosoma, Ehrenberg, anterior part of test modified to form operculum (Fig. 34, D) ; Ahyssascidia, Herdman, intestine on right side of branchial sac. The type genus of this section, Ascidia, has been described in detail above (Chapter II. p. 39), and Figs. 15 to 26 illustrate its structure and life-history. There are many species. Oiona intestinalis, Linn. (Fig. 40, B), is one of the commonest of British Ascidians, and lives readily in aqutiria. Sub-Fam. 3. Corellinae. — Stigmata curved and fo Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-ascidiae-simplices-ascidiidae-73-present-fig-15-p-40-bhodosoma-ehrenberg-anterior-part-of-test-modified-to-form-operculum-fig-34-d-ahyssascidia-herdman-intestine-on-right-side-of-branchial-sac-the-type-genus-of-this-section-ascidia-has-been-described-in-detail-above-chapter-ii-p-39-and-figs-15-to-26-illustrate-its-structure-and-life-history-there-are-many-species-oiona-intestinalis-linn-fig-40-b-is-one-of-the-commonest-of-british-ascidians-and-lives-readily-in-aqutiria-sub-fam-3-corellinae-stigmata-curved-and-fo-image232173998.htmlRMRDMC8E–. The Cambridge natural history. Zoology. ASCIDIAE SIMPLICES ASCIDIIDAE 73 present (Fig. 15, p. 40); Bhodosoma, Ehrenberg, anterior part of test modified to form operculum (Fig. 34, D) ; Ahyssascidia, Herdman, intestine on right side of branchial sac. The type genus of this section, Ascidia, has been described in detail above (Chapter II. p. 39), and Figs. 15 to 26 illustrate its structure and life-history. There are many species. Oiona intestinalis, Linn. (Fig. 40, B), is one of the commonest of British Ascidians, and lives readily in aqutiria. Sub-Fam. 3. Corellinae. — Stigmata curved and fo
![. The Cambridge natural history. Zoology. ASCIDIANS 2. The Parietal, or " peribranchial" type—seen in the Holo- somata, typically in the Botryllidae. The remarkable process of gemmation seen in the families Didemnidae and Diplosoniatidae, where the bud arises from at least two rudiments, the one stolonial or epicardiac in origin, and the. 'FiQ. 46. —A, Ascidiozooid from a Bot- ryllid colony ; B, ascidiozooid from a Distomid colony ; C. ascidiozooid from a Polyclinid colony. a, Anus ; at, atrial apertnre ; at.l, atrial languet ; 6r, branchial aper- ture ; cl, cloaca ; d.l, dorsal lang Stock Photo](https://c8.alamy.com/comp/RDMC5E/the-cambridge-natural-history-zoology-ascidians-2-the-parietal-or-quot-peribranchialquot-typeseen-in-the-holo-somata-typically-in-the-botryllidae-the-remarkable-process-of-gemmation-seen-in-the-families-didemnidae-and-diplosoniatidae-where-the-bud-arises-from-at-least-two-rudiments-the-one-stolonial-or-epicardiac-in-origin-and-the-fiq-46-a-ascidiozooid-from-a-bot-ryllid-colony-b-ascidiozooid-from-a-distomid-colony-c-ascidiozooid-from-a-polyclinid-colony-a-anus-at-atrial-apertnre-atl-atrial-languet-6r-branchial-aper-ture-cl-cloaca-dl-dorsal-lang-RDMC5E.jpg ". The Cambridge natural history. Zoology. ASCIDIANS 2. The Parietal, or " peribranchial" type—seen in the Holo- somata, typically in the Botryllidae. The remarkable process of gemmation seen in the families Didemnidae and Diplosoniatidae, where the bud arises from at least two rudiments, the one stolonial or epicardiac in origin, and the. 'FiQ. 46. —A, Ascidiozooid from a Bot- ryllid colony ; B, ascidiozooid from a Distomid colony ; C. ascidiozooid from a Polyclinid colony. a, Anus ; at, atrial apertnre ; at.l, atrial languet ; 6r, branchial aper- ture ; cl, cloaca ; d.l, dorsal lang Stock Photo")
. The Cambridge natural history. Zoology. ASCIDIANS 2. The Parietal, or " peribranchial" type—seen in the Holo- somata, typically in the Botryllidae. The remarkable process of gemmation seen in the families Didemnidae and Diplosoniatidae, where the bud arises from at least two rudiments, the one stolonial or epicardiac in origin, and the. 'FiQ. 46. —A, Ascidiozooid from a Bot- ryllid colony ; B, ascidiozooid from a Distomid colony ; C. ascidiozooid from a Polyclinid colony. a, Anus ; at, atrial apertnre ; at.l, atrial languet ; 6r, branchial aper- ture ; cl, cloaca ; d.l, dorsal lang Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-ascidians-2-the-parietal-or-quot-peribranchialquot-typeseen-in-the-holo-somata-typically-in-the-botryllidae-the-remarkable-process-of-gemmation-seen-in-the-families-didemnidae-and-diplosoniatidae-where-the-bud-arises-from-at-least-two-rudiments-the-one-stolonial-or-epicardiac-in-origin-and-the-fiq-46-a-ascidiozooid-from-a-bot-ryllid-colony-b-ascidiozooid-from-a-distomid-colony-c-ascidiozooid-from-a-polyclinid-colony-a-anus-at-atrial-apertnre-atl-atrial-languet-6r-branchial-aper-ture-cl-cloaca-dl-dorsal-lang-image232173914.htmlRMRDMC5E–. The Cambridge natural history. Zoology. ASCIDIANS 2. The Parietal, or " peribranchial" type—seen in the Holo- somata, typically in the Botryllidae. The remarkable process of gemmation seen in the families Didemnidae and Diplosoniatidae, where the bud arises from at least two rudiments, the one stolonial or epicardiac in origin, and the. 'FiQ. 46. —A, Ascidiozooid from a Bot- ryllid colony ; B, ascidiozooid from a Distomid colony ; C. ascidiozooid from a Polyclinid colony. a, Anus ; at, atrial apertnre ; at.l, atrial languet ; 6r, branchial aper- ture ; cl, cloaca ; d.l, dorsal lang
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] AsciDiANs nou THE CoASTS or Canada. >H covered surface. Up to about 15 mm. in diameter. In addition to the usual siphonal musculature, there are two circular bands (deficient ven- trally) of short fibres on either side of the median plane. From 18 to 37 tentacles, the largest bi-pinnate. Aperture of dorsal tubercle horseshoe-shaped; horns slightly inturned; opening between horns directed backwards and slightly towards right side. Dorsal lamina narrow, its margin smooth. Seven fol Stock Photo](https://c8.alamy.com/comp/REN0ND/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-1911-ascidians-nou-the-coasts-or-canada-gth-covered-surface-up-to-about-15-mm-in-diameter-in-addition-to-the-usual-siphonal-musculature-there-are-two-circular-bands-deficient-ven-trally-of-short-fibres-on-either-side-of-the-median-plane-from-18-to-37-tentacles-the-largest-bi-pinnate-aperture-of-dorsal-tubercle-horseshoe-shaped-horns-slightly-inturned-opening-between-horns-directed-backwards-and-slightly-towards-right-side-dorsal-lamina-narrow-its-margin-smooth-seven-fol-REN0ND.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] AsciDiANs nou THE CoASTS or Canada. >H covered surface. Up to about 15 mm. in diameter. In addition to the usual siphonal musculature, there are two circular bands (deficient ven- trally) of short fibres on either side of the median plane. From 18 to 37 tentacles, the largest bi-pinnate. Aperture of dorsal tubercle horseshoe-shaped; horns slightly inturned; opening between horns directed backwards and slightly towards right side. Dorsal lamina narrow, its margin smooth. Seven fol Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] AsciDiANs nou THE CoASTS or Canada. >H covered surface. Up to about 15 mm. in diameter. In addition to the usual siphonal musculature, there are two circular bands (deficient ven- trally) of short fibres on either side of the median plane. From 18 to 37 tentacles, the largest bi-pinnate. Aperture of dorsal tubercle horseshoe-shaped; horns slightly inturned; opening between horns directed backwards and slightly towards right side. Dorsal lamina narrow, its margin smooth. Seven fol Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-1911-ascidians-nou-the-coasts-or-canada-gth-covered-surface-up-to-about-15-mm-in-diameter-in-addition-to-the-usual-siphonal-musculature-there-are-two-circular-bands-deficient-ven-trally-of-short-fibres-on-either-side-of-the-median-plane-from-18-to-37-tentacles-the-largest-bi-pinnate-aperture-of-dorsal-tubercle-horseshoe-shaped-horns-slightly-inturned-opening-between-horns-directed-backwards-and-slightly-towards-right-side-dorsal-lamina-narrow-its-margin-smooth-seven-fol-image232801561.htmlRMREN0ND–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1911] AsciDiANs nou THE CoASTS or Canada. >H covered surface. Up to about 15 mm. in diameter. In addition to the usual siphonal musculature, there are two circular bands (deficient ven- trally) of short fibres on either side of the median plane. From 18 to 37 tentacles, the largest bi-pinnate. Aperture of dorsal tubercle horseshoe-shaped; horns slightly inturned; opening between horns directed backwards and slightly towards right side. Dorsal lamina narrow, its margin smooth. Seven fol
. The Cambridge natural history. Zoology. PODOPLEA AMPHARTHRANDRIA 67 Ascidiella scabra at Concarneau), in which the female has lost its segmentation, the mouth-parts and thoracic legs heing purely prehensile, and various species of JEnterocola, parasitic in the stomach of Compound Ascidians, in which the female is a mere sac incapable of free motion, while the male preserves its swim- ming powers and a general Cyclops-ioxm. (Fig. 34). We. Fig. 34.—EiUerucola fulgens. A, Ventral view of 9, X 35; B, side view of <J, x 106. Ahd.l, 1st abdominal segment ; Ant.l, Ant.S, 1st and 2nd antennae ; c Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/the-cambridge-natural-history-zoology-podoplea-ampharthrandria-67-ascidiella-scabra-at-concarneau-in-which-the-female-has-lost-its-segmentation-the-mouth-parts-and-thoracic-legs-heing-purely-prehensile-and-various-species-of-jenterocola-parasitic-in-the-stomach-of-compound-ascidians-in-which-the-female-is-a-mere-sac-incapable-of-free-motion-while-the-male-preserves-its-swim-ming-powers-and-a-general-cyclops-ioxm-fig-34-we-fig-34eiuerucola-fulgens-a-ventral-view-of-9-x-35-b-side-view-of-ltj-x-106-ahdl-1st-abdominal-segment-antl-ants-1st-and-2nd-antennae-c-image232163755.htmlRMRDKY6K–. The Cambridge natural history. Zoology. PODOPLEA AMPHARTHRANDRIA 67 Ascidiella scabra at Concarneau), in which the female has lost its segmentation, the mouth-parts and thoracic legs heing purely prehensile, and various species of JEnterocola, parasitic in the stomach of Compound Ascidians, in which the female is a mere sac incapable of free motion, while the male preserves its swim- ming powers and a general Cyclops-ioxm. (Fig. 34). We. Fig. 34.—EiUerucola fulgens. A, Ventral view of 9, X 35; B, side view of <J, x 106. Ahd.l, 1st abdominal segment ; Ant.l, Ant.S, 1st and 2nd antennae ; c
. A manual of zoology. Zoology. Fig. ,548, Fig. 549. Fig. 548,—A. MoJqula manhnttensis*; B, EugyrapiUuJaris.* (From Verrill.) Fig. oi9.—Hiilrijllus violaceus. (After Carpenter.) A, small colony of eighteen indi- vidual groups; i?, two individual groups somewhat enlarged. with its own test; Perophora* CYNTmiD^, test leather}', oral and atrial openings four-lobed; Gynthia* MolgduDjE, oral opening, six-lobed, atrial four-lobed. 3Iolgu7a,* Eugyra* Sub Order II. SYNASCIDI^. Compound ascidians consisting of numerous small individuals imbedded in a common cellulose tunic and forming considerable crus Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/a-manual-of-zoology-zoology-fig-548-fig-549-fig-548a-mojqula-manhnttensis-b-eugyrapiuujaris-from-verrill-fig-oi9hiilrijllus-violaceus-after-carpenter-a-small-colony-of-eighteen-indi-vidual-groups-i-two-individual-groups-somewhat-enlarged-with-its-own-test-perophora-cyntmid-test-leather-oral-and-atrial-openings-four-lobed-gynthia-molgdudje-oral-opening-six-lobed-atrial-four-lobed-3iolgu7a-eugyra-sub-order-ii-synascidi-compound-ascidians-consisting-of-numerous-small-individuals-imbedded-in-a-common-cellulose-tunic-and-forming-considerable-crus-image232346333.htmlRMRE0839–. A manual of zoology. Zoology. Fig. ,548, Fig. 549. Fig. 548,—A. MoJqula manhnttensis*; B, EugyrapiUuJaris.* (From Verrill.) Fig. oi9.—Hiilrijllus violaceus. (After Carpenter.) A, small colony of eighteen indi- vidual groups; i?, two individual groups somewhat enlarged. with its own test; Perophora* CYNTmiD^, test leather}', oral and atrial openings four-lobed; Gynthia* MolgduDjE, oral opening, six-lobed, atrial four-lobed. 3Iolgu7a,* Eugyra* Sub Order II. SYNASCIDI^. Compound ascidians consisting of numerous small individuals imbedded in a common cellulose tunic and forming considerable crus
![. Outlines of zoology. Zoology. GENERAL NOTES ON TUNIC ATA. 407 respiratory current as in the Ascidians, and the gill-slits may be few in N M DO. Fig. 176A.—" Nurse" of Doliohim m&lleri. —After Uljanin. I., inhalant, E., exhalant aperture; C, ciliated band round pharynx (P); En., endostyle; O., otocyst; N., nerve-gang- lion; H., heart; CE., (esophageal opening; D., stomach; A., anus; CI., cloaca; DO., dorsal organ ; M., muscle bands. number, or, as in Salpa, may be represented by two large holes in the walls of the pharynx. Further, the hermaphroditism is modified by the. Please Stock Photo](https://c8.alamy.com/comp/RDNYRY/outlines-of-zoology-zoology-general-notes-on-tunic-ata-407-respiratory-current-as-in-the-ascidians-and-the-gill-slits-may-be-few-in-n-m-do-fig-176aquot-nursequot-of-doliohim-mamplleri-after-uljanin-i-inhalant-e-exhalant-aperture-c-ciliated-band-round-pharynx-p-en-endostyle-o-otocyst-n-nerve-gang-lion-h-heart-ce-esophageal-opening-d-stomach-a-anus-ci-cloaca-do-dorsal-organ-m-muscle-bands-number-or-as-in-salpa-may-be-represented-by-two-large-holes-in-the-walls-of-the-pharynx-further-the-hermaphroditism-is-modified-by-the-please-RDNYRY.jpg ". Outlines of zoology. Zoology. GENERAL NOTES ON TUNIC ATA. 407 respiratory current as in the Ascidians, and the gill-slits may be few in N M DO. Fig. 176A.—" Nurse" of Doliohim m&lleri. —After Uljanin. I., inhalant, E., exhalant aperture; C, ciliated band round pharynx (P); En., endostyle; O., otocyst; N., nerve-gang- lion; H., heart; CE., (esophageal opening; D., stomach; A., anus; CI., cloaca; DO., dorsal organ ; M., muscle bands. number, or, as in Salpa, may be represented by two large holes in the walls of the pharynx. Further, the hermaphroditism is modified by the. Please Stock Photo")
. Outlines of zoology. Zoology. GENERAL NOTES ON TUNIC ATA. 407 respiratory current as in the Ascidians, and the gill-slits may be few in N M DO. Fig. 176A.—" Nurse" of Doliohim m&lleri. —After Uljanin. I., inhalant, E., exhalant aperture; C, ciliated band round pharynx (P); En., endostyle; O., otocyst; N., nerve-gang- lion; H., heart; CE., (esophageal opening; D., stomach; A., anus; CI., cloaca; DO., dorsal organ ; M., muscle bands. number, or, as in Salpa, may be represented by two large holes in the walls of the pharynx. Further, the hermaphroditism is modified by the. Please Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/outlines-of-zoology-zoology-general-notes-on-tunic-ata-407-respiratory-current-as-in-the-ascidians-and-the-gill-slits-may-be-few-in-n-m-do-fig-176aquot-nursequot-of-doliohim-mamplleri-after-uljanin-i-inhalant-e-exhalant-aperture-c-ciliated-band-round-pharynx-p-en-endostyle-o-otocyst-n-nerve-gang-lion-h-heart-ce-esophageal-opening-d-stomach-a-anus-ci-cloaca-do-dorsal-organ-m-muscle-bands-number-or-as-in-salpa-may-be-represented-by-two-large-holes-in-the-walls-of-the-pharynx-further-the-hermaphroditism-is-modified-by-the-please-image232208143.htmlRMRDNYRY–. Outlines of zoology. Zoology. GENERAL NOTES ON TUNIC ATA. 407 respiratory current as in the Ascidians, and the gill-slits may be few in N M DO. Fig. 176A.—" Nurse" of Doliohim m&lleri. —After Uljanin. I., inhalant, E., exhalant aperture; C, ciliated band round pharynx (P); En., endostyle; O., otocyst; N., nerve-gang- lion; H., heart; CE., (esophageal opening; D., stomach; A., anus; CI., cloaca; DO., dorsal organ ; M., muscle bands. number, or, as in Salpa, may be represented by two large holes in the walls of the pharynx. Further, the hermaphroditism is modified by the. Please
![. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1,1. .h} 114 Transactions of the Canadian Institute. [vol. ix land Straits. PhaUusia ceratodes grows in large beds in the bay south of Brandon Rocks and also in a sponge bed near the entrance to the bay. Elsewhere only occasional specimens were obtained. Chelyosomatidae. Chdyosoma productum is occasional at low tide and abundant in deeper water. C. columbianum was found in from 10 to 20 fathoms but was not abundant. CoreUa inflata was growing m numbers near low water mark and C. rugosa in Stock Photo](https://c8.alamy.com/comp/REN0PR/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-11-h-114-transactions-of-the-canadian-institute-vol-ix-land-straits-phauusia-ceratodes-grows-in-large-beds-in-the-bay-south-of-brandon-rocks-and-also-in-a-sponge-bed-near-the-entrance-to-the-bay-elsewhere-only-occasional-specimens-were-obtained-chelyosomatidae-chdyosoma-productum-is-occasional-at-low-tide-and-abundant-in-deeper-water-c-columbianum-was-found-in-from-10-to-20-fathoms-but-was-not-abundant-coreua-inflata-was-growing-m-numbers-near-low-water-mark-and-c-rugosa-in-REN0PR.jpg ". Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1,1. .h} 114 Transactions of the Canadian Institute. [vol. ix land Straits. PhaUusia ceratodes grows in large beds in the bay south of Brandon Rocks and also in a sponge bed near the entrance to the bay. Elsewhere only occasional specimens were obtained. Chelyosomatidae. Chdyosoma productum is occasional at low tide and abundant in deeper water. C. columbianum was found in from 10 to 20 fathoms but was not abundant. CoreUa inflata was growing m numbers near low water mark and C. rugosa in Stock Photo")
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1,1. .h} 114 Transactions of the Canadian Institute. [vol. ix land Straits. PhaUusia ceratodes grows in large beds in the bay south of Brandon Rocks and also in a sponge bed near the entrance to the bay. Elsewhere only occasional specimens were obtained. Chelyosomatidae. Chdyosoma productum is occasional at low tide and abundant in deeper water. C. columbianum was found in from 10 to 20 fathoms but was not abundant. CoreUa inflata was growing m numbers near low water mark and C. rugosa in Stock Photohttps://www.alamy.com/image-license-details/?v=1https://www.alamy.com/ascidians-from-the-coasts-of-canada-microform-sea-squirts-tunicata-ascidies-tuniciers-tuniciers-11-h-114-transactions-of-the-canadian-institute-vol-ix-land-straits-phauusia-ceratodes-grows-in-large-beds-in-the-bay-south-of-brandon-rocks-and-also-in-a-sponge-bed-near-the-entrance-to-the-bay-elsewhere-only-occasional-specimens-were-obtained-chelyosomatidae-chdyosoma-productum-is-occasional-at-low-tide-and-abundant-in-deeper-water-c-columbianum-was-found-in-from-10-to-20-fathoms-but-was-not-abundant-coreua-inflata-was-growing-m-numbers-near-low-water-mark-and-c-rugosa-in-image232801599.htmlRMREN0PR–. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. 1,1. .h} 114 Transactions of the Canadian Institute. [vol. ix land Straits. PhaUusia ceratodes grows in large beds in the bay south of Brandon Rocks and also in a sponge bed near the entrance to the bay. Elsewhere only occasional specimens were obtained. Chelyosomatidae. Chdyosoma productum is occasional at low tide and abundant in deeper water. C. columbianum was found in from 10 to 20 fathoms but was not abundant. CoreUa inflata was growing m numbers near low water mark and C. rugosa in
