URINOGENITAL ORGANS 



351 



Fifi 



278a. — Diagram of the Primitive Condition of the Kidney in an 

 Elasmobkanoh 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.f 



Fir,. 278b. — Diagram of the Arrangement of the Urinogenital Organs in 

 an Adult Female Elasmobranch. (After Balfour. ) 



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

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

 nephridial tubes form the functional kidney ; ov, ovary. 



S.f 



Fig. 278c. Diagram of the Arrangement of the Urinogenital Orcan.s in 



AN Adult Male Elasmobranch. (After Balfour. ) 



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

 sevvincr as vas deferens ; s.t, nephridial tubes : two of tliem are represented 

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

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

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

 efferentia ; h; longitudinal canal of the Wolffian body. 



