. A manual of zoology. Zoology. IV. POLYZOA: ECTOPROCTA 285 circle of tentacles, arising from the edge of the cup, enclose the peristomial area in which are both mouth and anus, and between these the excretory and re- productive organs open. The space between the horseshoe-shaped intestine and the body surface is filled by a parenchyma containing muscle cells, and correspondingly the excretory organs are protonephridia. UrnalcHa'' fresh- water. PediceUina* Loxosoina, marine. Sub Class II. Ectoproda. The Ectoprocta have a spacious, often ciliated, coelom between the alimentary canal and skin, s
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. A manual of zoology. Zoology. IV. POLYZOA: ECTOPROCTA 285 circle of tentacles, arising from the edge of the cup, enclose the peristomial area in which are both mouth and anus, and between these the excretory and re- productive organs open. The space between the horseshoe-shaped intestine and the body surface is filled by a parenchyma containing muscle cells, and correspondingly the excretory organs are protonephridia. UrnalcHa'' fresh- water. PediceUina* Loxosoina, marine. Sub Class II. Ectoproda. The Ectoprocta have a spacious, often ciliated, coelom between the alimentary canal and skin, so that these are separated and have a certain amount of independence (fig. 274). On this account has arisen a pecu- liar method (morphologically indefensible) of treating them as two in- dividuals, polypid, the intestine and tentacles; cystid the rest, especially the body wall and skeleton.. Fig. 274.—Fluslra membranacea (after Nitsche), a single animal, a. anus; ek, ectocyst; en, entocyst;/, funiculus; g, ganglion; k, collar which permits com]jlete retrac- tion; m, stomach, also tlermal muscular sac; 0, oesophagus. A, avicularium; B, vibracu- larium of Bugula (after Claparede). The cystid is cup-shaped or saccular. It consists of an endocyst—• the body wall—and an ectocyst—a cuticular skeleton, often strongly calcified, secreted by the ectoderm. The ectocyst covers only the base and side walls of the endocyst, leaving the outer end soft, thus forming a sort of collar into which the tentacles and adjacent parts of the cystid can be retracted. The opening thus formed in the ectocyst in many species (Chilostomata) can be closed by a lid (operculum). The circle of tentacles surrounds the mouth alone, while the anus is outside near the collar. The. 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 not perfectly resemble the original work.. Hertwi