291 



COMPARATIVE ANATOMY. 



atrophied. The many-coiled end of the duct serves as a seminal 

 vesicle (Fig. 153, vd), 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 

 ccelom, 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 neai', 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 Limnadia is beset with short pouch-like diverticula, 

 which form a lobate gland of a larger 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 Arthro- 

 7/ 



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. 151, 

 C) 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 excretory duct arises. This has 

 either an orifice of its own, or is united with its fellow of the other 

 side in front of the orifice. 



§ 228. 



Among the Thoracostraca the Schizopoda (Mysis) are provided 

 with the simpler kind of generative organs. The female organs 

 (Fig. 154, A) consist of an unpaired germ-gland (n) } to the sides of 

 which oviducts are attached, and these are widened out anteriorly into 



Fig. 154. Female generative organs in Crustacea. 



A Of Mysis. B Of Sapphirina. G Of Oniscus. 



o Ovary, od Oviduct, u Uterus. 



