URINOGENITAL ORGANS 



351 



FIG. 278A. DIAGRAM or THE PRIMITIVE CONDITION OF THE KIDNEY IN AN 

 ELASMOBRANCII EMBRYO. (After Balfour.) 



pd, pronephric duct : it opens at o into the body-cavity, and its other extremity 

 communicates with the cloaca ; x, line along which the division appears which 

 separates the pronephric duct into the Wolffian duct above, and the Miillerian 

 duct below ; s.t, nephridial tubes : they open at one end in the body-cavity, 

 and at the other into the Wolffian duct. 



s.t- 



FIG. 278s. DIAGRAM OF THE ARRANGEMENT OF THE URINOGENITAL ORGANS IN 

 AX ADULT FEMALE ELASMOBRANCH. (After Balfour.) 



m.d, Miillerian duct ; w.d, Wolffian duct ; d, urinary duct ; s.t, nephridial tubes : 

 five of them are represented with openings into the body-cavity : the posterior 

 nephridial tubes form the functional kidney ; ov, ovary. 



S.t 



FIG. 278c. DIAGRAM OF THE ARRANGEMENT OF THE URINOGENITAL ORGANS IN 

 AN ADULT MALE ELASMOBRANCH. (After Balfour. ) 



m.d, rudiments of Miillerian duct ; w.d, Wolffian duct, marked vd in front, and 

 serving as vas deferens ; s.t, nephridial tubes : two of them are represented 

 with openings into the body-cavity : the anterior tubules give rise to the 

 parorchis or epididymis and the posterior ones to the functional kidney ; d, 

 urinary duct ; t, testis ; nt, canal at the base of the testis ; VE, vasa 

 efferent ia ; Ic, longitudinal canal of the Wolffian body. 



