URINARY SYSTEM OF MAMMALS. 



G09 



substance, ib. b 9 c ; the tubuli terminate at the apex of a mammilla, 

 d, which projects into an infundibulum. The infundibula are pro- 

 longed, and unite to form the ureter which comes out at the medial 

 and hinder surface of the kidney and enters the neck of the uri- 

 nary bladder. 



In most quadrupeds this reservoir is more pendulous, has a 

 more complete covering of peritoneum, than in Man. The oblique 

 valvular course of the ureters through its coats is common to the 

 Mammalian class. The monotremes are the sole exceptions ; in 

 them the ureters, fig. 485, /, 2, do 



j or 



not terminate in the bladder, k, but 

 in the urogenital canal, c, the ori- 

 fice of the spermduct or oviduct, m, 

 intervening between that of the 

 ureter and the bladder. The urine 

 may dribble out with the faeces, or 

 may pass by a retrograde course 

 into the bladder ; but, in either 

 case, it is expelled per cloacam not 

 per urethram : the penis in the 

 male subserving the conveyance of 

 the semen only. In all other 

 mammals both urine and semen are 

 carried out by the urethral canal 

 in the male; and, in some Insectivora (Shrews, Moles) and Quad- 

 rumana (Slow Lemurs), the clitoris in the female is similarly tra- 

 versed by a canal, which here, however, is exclusively for the 

 urine. The vaginal orifice intervenes between the prominent and 

 perforate clitoris, figs. 485, 546, c, and the anus. 



Clitoris, vagina and vent, Shrew. 



VOL. III. 



R R 



