712 AMPHIBIA. 



In most Urodeles the peritoneal openings connected with the primary 

 generative Malpighian bodies atrophy, but in Spelerpes they persist. In 

 the Cceciliidas they also remain in the adult state. 



With reference to the development of these parts little is 

 known except that the testicular network grows out from the 

 primary Malpighian bodies, and becomes united with the testis. 

 Embryological evidence, as well as the fact of the persistence of 

 the peritoneal funnels of the generative region in the adults 

 of some forms, proves that the testicular network is not developed 

 from the peritoneal funnels. 



Rudiments of the testicular network are found in the female Cceciliida: 

 and in the females of many Urodela (Salamandra, Triton). These rudi- 

 ments may in their fullest development consist of a longitudinal canal and 

 of transverse canals passing from this to the Malpighian bodies, together 

 with some branches passing into the mesovarium. 



Amongst the Urodela the collecting tubes of the hinder non-sexual part 

 of the Wolffian body, which probably represents a rudimentary metanephros, 

 undergo in the male sex a change similar to that which they usually undergo 

 in Elasmobranchii. Their points of junction with the Wolffian duct are 

 carried back to the hindermost end of the duct (fig. 400 B), and the collecting 

 tubes themselves unite together into one or more short ducts (ureters) before 

 joining the Wolffian duct. 



In Batrachoseps only the first collecting tube becomes split off in 

 this way ; and it forms a single elongated ureter which receives all the 

 collecting tubes of the posterior segmental tubes. In the female and in 

 the male of Proteus, Menobranchus, and Siren the collecting tubes retain 

 their primitive transverse course and open laterally into the Wolffian duct. 

 In rare cases (Ellipsoglossus, Spengel] the ureters open directly into the 

 cloaca. 



The urinary bladder of the Amphibia is an outgrowth of the 

 ventral wall of the cloacal section of the alimentary tract, and is 

 homologous with the allantois of the amniotic Vertebrata. 



The subjoined diagram (fig. 400) of the urogenital system of 

 Triton illustrates the more important points of the preceding 

 description. 



In the female (A) the following parts are present : 



(1) The Miillerian duct or oviduct (od) derived from the 

 splitting of the segmental duct. 



(2) The Wolffian duct (sng) constituting the portion of the 

 segmental duct left after the formation of the Miillerian duct. 



(3) The mesonephros (r), divided into an anterior sexual part 



