258 



ME. W. P. PYCRAFT ON THE MOEPHOLOGY AND 



chamber, though this is but small and not very sharply denned. In this succession of 

 chambers therefore, as Dr. Gadow has pointed out, Struthio resembles some Saurians 

 and young Crocodiles. 



In Struthio, defalcation and micturition are separate acts, and the urine, instead of 

 passing from the uro- to the coprodseum, is transferred to the bursa Fabricii, which, 

 unlike that of all other birds, is of considerable size and remains permanently open. 

 Its function, acting as a physiological dorsal bladder, is unique. A true allantoic 

 bladder, communicating directly with the ureters, is wanting in the Aves. 



The cloacal aperture of the Palceognathce, as in 'Neognathw, is round, not transverse 

 as in Beptilia. 



Pis- 9. 



The terminal end of the alimentary canal of Casuarivs violicollis, to show the cloaca and its divisions 

 into copro-, uro-, and proctodaeum and the form and position of the bursa Fabricii. 



h.f. = bursa Fabricii. 

 c.d. = coprodasuni. 

 u.d. = urodasum. 

 p.d. = proctodseum. 



cl. = clitoris. 

 ovid. = aperture of oviduct. 



m. = aperture of ureter. 



b. The Bursa. 



The bursa Fabricii of the Palceognathce has been very carefully studied by Forbes 

 [20] and Wenckebach [97]. 



In the Palceognathce — save only in Apteryx — as Forbes [20 a] has shown, the 

 bursa in young birds is of considerable size. Furthermore, he held that it differed 



