DEVELOPMENT OF ELASMOBRANCH FISHES. 



285 



which the semen is conveyed to the Wolffian duct (v. d). The 

 Wolffian duct itself becomes much contorted and acts as vas 

 deferens. 



Fig. 8. 



Diagram of the arrangement of the Urinogenital Organs in an adult 

 Female Elasmobranch. 



m.d. Miillerian duct ; w.d. "Wolffian duct ; s.t. glandular tubuli ; 



five of them are represented with openings into the body-cavity ; d. duct of 

 the posterior segmental tubes; ov. ovary. 



In the woodcuts, fig. 8 and 9, are diagrammatically repre- 

 sented the chief constituents of the adult urinos^enital oro-ans 

 in the two sexes. In the adult female, fig. 8, there are present 

 the following parts : 



(1) The oviduct or Miillerian duct {m.d) split off from the 

 segmental duct of the kidneys. Each oviduct opens at its anterior 

 extremity into the body-cavity, and behind the two oviducts 

 have independent communications with the general cloaca. 



(2) The Wolffian ducts [lu.d), the other product of the seg- 

 mental ducts of the kidneys. They end in front by becoming 

 continuous with the tubulus of the anterior segment of the 

 Wolffian body on each side, and unite behind to open by a 

 common papilla into the cloaca. The Wolffian duct receives 

 the secretion of the anterior part of the primitive kidney which 

 forms the Wolffian body. 



(3) The ureter {d) which carries off the secretion of the 

 kidney proper. It is represented in my diagram in its most 

 rare and differentiated condition as a single duct. 



(4) The glandular tubuli {s.t), some of which retain their 

 original opening into the body-cavity, and others are without 

 them. They are divided into two groups, an anterior forming 



