492 FISHES. 



the cloaca ; in the female they open into little bladders the 

 dilated ends of the Wolffian ducts, and thence by a common 

 aperture into the cloaca. 



The archinephric or segmental duct of each side divides 

 into a Wolffian and a Mlillerian duct. The Wolffian duct 

 becomes in the male the vas deferens, in the female an 

 unimportant mesonephric duct ; the Miillerian duct becomes 

 in the female the oviduct, and in the male a mere rudiment. 



The muscles and other organs of Elasmobranchs retain 

 considerable quantities of nitrogenous waste products. 



FIG. 163. Urinogenital organs of female Skate. (In 

 part after MONRO.) 



/., Aperture of united oviducts; W.D.> Wolffian duct; <??./., 

 ovary; O.D.G., oviducal gland; ., egg in mermaid's purse; BL, 

 bladder at base of Wolffian ducts (arrow into cloaca); K., kidney 

 (arrow from base of oviduct into cloaca). 



Reproductive System. 



The male organs or testes lie on each side of the cardinal 

 sinus, moored by a fold of peritoneum. Spermatozoa pass 

 from the testis by vasa efferentia into a tube surrounded 



