. Elements of Comparative Anatomy. 294 COMPAEATIVE ANATOMY. atrophied. The many-coiled end of the duct serves as a seminal vesicle (Fig. 153, vcl), in which the spermatophores are formed. In the Branchiopoda the germ-glands are separate tubes which lie beside the enteric canal. In the Cladocera, where they are directly continuous with the scarcely separable efferent duct, they are simple; the duct of both male and female organs opens near the end of the body. The Phyllopoda resemble them in this. Sometimes the testes or ovaries occupy the hinder part only of the coelom, while the duct is given
. Elements of Comparative Anatomy. 294 COMPAEATIVE ANATOMY. atrophied. The many-coiled end of the duct serves as a seminal vesicle (Fig. 153, vcl), in which the spermatophores are formed. In the Branchiopoda the germ-glands are separate tubes which lie beside the enteric canal. In the Cladocera, where they are directly continuous with the scarcely separable efferent duct, they are simple; the duct of both male and female organs opens near the end of the body. The Phyllopoda resemble them in this. Sometimes the testes or ovaries occupy the hinder part only of the coelom, while the duct is given off from their anterior end (Artemia, Branchipus) and bends backwards, or they begin farther forwards, and give off the excretory duct at, or near, their posterior end (Holopedium). In the former an enlargement of the oviduct serves as the uterus, while a swelling on the seminal duct forms the seminal vesicle. This simpler form of the generative organs is modified in the Phyllopoda, owing to the enlargement of the germinal glands. The ovary of Limuadia is beset with short pouch-like diverticula, which form a lobate gland of a lai'ger size in Apus, owing to the larger number of branches in it. This organ also serves as a uterus for the ripe eggs. The testis has the same morphological characters. Among the Ai'thro- >^ 'a straca the generative organs are generally double, each side pro- vided with a separate orifice. In the Amphi- poda the female organs consist of simple tubes which open as a rule at the base of the fifth thoracic segment. In the Isopoda (Fig. 154, G) the tube ends blindly in front and behind, and the effer- ent duct arises on the course of it. The ends of the tubes are to be regarded as true germ-glands, while* the rest or largest portion resembles an oviduct or uterus. The male organs are similar, but in the Isopoda they are peculiar in character, several testicular tubes (Fig. 155, B) uniting into a special portion, from which a narrower and much-coiled
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