326 



COMPARATIVE ANATOMY. 



The ovaries, however, never move in the course of development 

 further backwards than the pelvis ; but each testis may pass out 

 of the abdomen through a space in its wall, the inguinal canal; 

 it thus comes to lie within a purse-like appendage of the hypo- 

 gastric region called the scrotal sac. The two scrotal sacs may 



-72T' 



FIG. 256. MALE UKINOGENITAL APPARATUS OF THE HEDGEHOG (Erinaccus). 

 N, kidney ; Ur, ureters ; B, urinary bladder ; Pm, membranous portion of urino- 

 genital tube ; Cpc, corpus cavernosum ; Pp, prepuce ; Gp, glans penis ; PI), 

 preputial glands ; Cd, Cowper's glands ; Pr, Pr l , the different lobes of the 

 prostate ; Sb, vesicula seminalis ; Ho, testis ; Ep, epididymis ; Vd, Vd l , vas 

 deferens. 



remain separate, or unite to form a scrotum. In passing out, 

 the testes carry with them a portion of the peritoneum the 

 tunica vaginalis: if the inguinal canals remain open, they 

 may be at times again withdrawn into the abdomen (e.g. in 

 Rodentia); this is effected by means of the cremaster muscle, 



