THE ANATOMY OF POLYPTEEUS. 



329 



genital duct in the male, opening into the ureter on its lateral wall shortly before its 

 termination (text-fig. 6). 



The resemblance of these ducts in the male and female is brought out still more 

 strongly by a study of the quite young fish 9 cm. in length. Apart from the fact 

 that the oviduct opens into the body-cavity, the arrangements in the two sexes are 

 identical. 



Pig- 5. Pig. 6. 



w.J 



— trd 



•p.ap.od.—e^ 



Pig. 5. — Diagram of the urinogenital organs in the male Polypiems. 

 Pig. 6. — Diagram of the urinogenital organs in the female Polypterus. 



g.ap., genital aperture ; Tc., kidney ; ov., ovary ; ovd., oviduct ; p.ap.od., peritoneal aperture of oviduct ; 

 s.vg.s., septum of urinogenital sinus : t., testis ; t.d., testis-duct ; t.r., testis-ridge ; t.r.d., duct of testis- 

 ridge ; u., ureter ; v.d., vas deferens. 



The question as to whether these ducts are both homologous with the Miillerian 

 ducts of Elasmobranchs, Amphibia, and Amniota can of course only be settled by a 

 knowledge of their actual origin. 



The fact remains, however, that in this most primitive fish the arrangement of the 

 genital ducts is nearly identical in the two sexes, and would seem to substantiate the 



