441 



BLA.T)DEB.S AXD PERITOXEAL CANALS IX CHELOXIA. 



ureters opening by distinct orifices into the cloaca, they have pro- 

 bably an origin quite distinct from the Miillerian ducts ; and the 

 likelihood is that they are strictly homologous with the abdominal 

 pore of the Selachians and Ganoids. The true nature and origin 

 of these pores is little understood; but Mr. F, M. Balfour* has 

 suggested that they are probably the openings of a pair of seg- 

 mental organs. Embryology, however, must be the ultimate in- 

 terpreter of their origin and meaning. 



Diagram illustrating the cloaca! bladders and the peritoneal canals of Chelonia. 



B, urinary bladder ; R, rectum ; C. B, cloacal bladder (arrows are represented 

 on either side entering these from the cloaca); P. C, peritoneal canals (arrow* 

 descend and have exit therefrom at o, orifice) ; jp, peritoneum ; p'^, perito- 

 neal covering of bladder ; V, ureter; v.d, vas deferens ; ug, urinogenital 

 groove ; c, clitoris. 



* Jonrn. Anat. Phj.=. vol. x. pt. 1. 1875, p. 34. 



