35© 



COMPARATIVE MORPHOLOGY OF VERTEBRATES 



In the ichthyopsida, other than elasmobranchs and amphibia, the 

 sperm is carried to the exterior in other ways, and there is no connex- 

 ion of the testes with the excretory organs. In the cyclostomes the 

 sperm escapes from the testes into the coelom and then is passed to 

 the exterior by way of the abdominal pores (p. 19) which in the 

 lampreys open into a cavity (sinus urogenitalis) which also receives 

 the hinder ends of the Wolffian ducts. In the myxinoids the pores 



Fig. 373. — Diagrams of urogenital organs of male fishes, after Goodrich. A, 

 Acipenser {Lepidosteus and Amia similar, but lack the oviduct); B, teleosts; C, Polyp- 

 terus; D, Protopterus; E, urogenital openings of female salmon, a, anus; ap, abdominal 



{)ore; c6, cloacal ('urinary') bladder; e, vasa efferentia; gp, genital pore (papilla); /, 

 ongitudinal duct; It, longitudinal testis duct; tn, mesonephros; md, Miillerian(?) 

 duct; r, rectum; re, renal corpuscle; s, urogenital sinus; /, testis; u, up, urinary pore; 

 ugp, urogenital pore; v, vas deferens; w, WolflBan duct. 



are united, and they open to the exterior behind the anus and be- 

 tween it and the urinary openings. 



The conditions found in the sturgeons (fig. 373, A) and in Polypierus give 

 a possible explanation to the aberrant structures of the teleosts. In the first 

 group can be made out the vasa efiferentia and the two longitudinal canals 

 connecting them, these extending the whole length of the testis. In Polyp- 

 ierus (fig. 373, C) the connexion between the testis and mesonephros is con- 

 fined to the hinder portion of organs, the anterior vasa efiferentia and the 

 longitudinal canal disappearing in front, the longitudinal testicular canal taking 



