372 



COMPARATIVE ANATOMY 



CHAP. 



Entomostraca.— In the Branchiopoda, the germ glands are paired ; in Bra^icldpus 

 (Fig. 191, p. 288) they are tubular and lie in the abdomen ; in Apus they are richly 

 branched and lie in the limb-bearing division of the trunk. In Branchipus the ovi- 

 ducts are widened out at their ends and enter a uterus in which the eggs remain for a 

 time receiving a. shell yielded by special uterine glands. The uterus lies in a pouch 

 formed by a concrescence of genital prominences, the modified limbs of the two genital 

 segments (12th and 13th trunk segments). 



The vasa deferentia are also widened out at their ends (sperm vesicles) and enter 

 a muscular ductus ejaculatorius, which, when the penis is evaginated, is drawn out 



R 



Fig. 247.— Genital organs 

 of Lernanttropus (after 

 Heider). A, Female, B, male 

 organs, ov, Ovary ; od, ovi- 

 duct ; kd, cement glands ; 

 rs, receptaculum seminls ; 

 go, sexual apertui-e ; p, pore 

 canal to the sperniatophore ; 

 &/:, brown body ; sp, sperma- 

 tophore ; t, testis ; vd, "\'as 

 deferens ; st, sperniatophore 

 pouch. 



with it inside it. The penis is an ectodermal outgrowth of the second genital 

 prominence. 



In the Gladocera, the ovaries and testes are simple paired tubes. The oviducts 

 emerge dorsally into the posterior end of the brood cavity (see on Care of the Brood, 

 Ji. 379). The vasa deferentia with the ductus ejaculatorius emerge by paired 

 apertures on the ventral side of the limbless posterior division of the body. 



In the Ostracoda the germ glands are paired, as also are the vasa deferentia and 

 the oviducts. The testes often fall into several tubes. The ductus ejaculatorius with 

 the sperm vesicle may be unpaired {Cypridina). The copulatory apparatus of the 

 male is to some extent complicated (transformed hindermost limbs). In the female, 

 two genital prominences corresponding with those of the male contain the receptacula 

 seminis. In Cijpris the ovarial tubes extend into the shell-fold. 



