UROGENITAL SYSTEM. 



323 



the longitudinal testicular canal of other vertebrates) which runs in 

 the membrane (mesorchium) supporting the testis, back to the external 

 opening, which is either directly to the exterior between the urinary 

 opening and the anus (fig. 328) or into a urogenital sinus (fig. 321, B). 



This view is farther supported by the relations in the dipnoi. In 

 Ceratodus there are numerous vasa efferentia which extend from the 

 testis into the mesonephros. In Lepidosiren the efferent ductules are 



FIG. 325. Diagrams of urogenital organs of male fishes, after Goodrich. A, Acipenser 

 (Lepidosteus and Amia similar, but lack the oviduct); B, teleosts; C, Polypterus; D, Pro- 

 topterus; E, urogenital openings of female salmon, a, anus; ap, abdominal pore; cb t 

 cloacal ('urinary') bladder; e, vasa efferentia; gp, genital pore (papilla); m, mesonephros; 

 md, Miillerian(?) duct; r, rectum; re, renal corpuscle; s, urogenital sinus; /, testis; u, up, 

 urinary pore; ugp, urogenital pore; v, vas deferens; w, Wolffian duct. 



fewer in number and they arise from a posterior degenerate portion 

 of the testis, while in Protopterus (fig. 325, D) there is but a single 

 vas efferens on either side and this passes through the posterior end 

 of the Wolffian body. 



Oviducts. In the elasmobranchs the Miillerian duct, which, as 

 described above, arises by a splitting of the pronephric duct, serves 

 as the oviduct. After separation from the Wolffian duct this opens 

 in front into the coelom by means of the pronephric tubules and their 



