. Elementary text-book of zoology. Zoology. 466 CRUSTACEA. filaments and hairs on the surface of the anterior antenna? have the value of olfactory organs; the antenna? function as tactile organs, as do also the palps of the jaws, the maxillipeds and the legs. The generative organs are paired and lie in the thorax or in the abdomen (titomatopoda), and, as a rule, are connected across the middle line by a median portion. The female organs consist of two ovaries and two oviducts, which open on the basal joint of the antepen- ultimate pair of ambulatory legs or on the sternal region between these
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. Elementary text-book of zoology. Zoology. 466 CRUSTACEA. filaments and hairs on the surface of the anterior antenna? have the value of olfactory organs; the antenna? function as tactile organs, as do also the palps of the jaws, the maxillipeds and the legs. The generative organs are paired and lie in the thorax or in the abdomen (titomatopoda), and, as a rule, are connected across the middle line by a median portion. The female organs consist of two ovaries and two oviducts, which open on the basal joint of the antepen- ultimate pair of ambulatory legs or on the sternal region between these appendages (fig. 365, a). The testes (fig. 365, /;) are composed of numerous sacs and blind tubes, and, like the ovaries, are connected by a median portion; there are two vasa deferentia, often much coiled, which open on the basal joint of the last pair of ambulatory legs, more rarely on the sternum, and occasionally on a special copulatory organ (Schi- zopoda). The first, or the first and second, pair of abdominal feet act as intromittent or- gans. The eggs either pass into a brood-poiich formed by lamellar ap- pendages of the thoracic legs (Cumacea, Schizo- 2)oda), or become at- tached by means of the cementing secretion of special glands to the hairy abdominal feet of the female, where they remain until they are hatched (Decapodfi}. Development.—Most of the T/toracostraca undergo a metamor- phosis which may be more or less complicated. The Cumacea, some Schizo£>oda (Mysidea) and the fresh-water Decapoda (Astacus) leave the egg membranes with the full number of segments and appen- dages. All the Stomatopoda, on the contrary, as well as most of the Decapoda, are hatched as larva? ; the latter in the so-called Zo(ca form with only seven pairs of appendages in the antei-ior region of the body (there are two pairs of antenna?, mandibles, two pairs of maxilla1, and two pairs of maxillipeds), without the last six thoracic segments and with a long abdomen destitute of appendag