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 scrotalsac. The two scrotal sacs may 



FIG. 256. MALE URINOGENITAL AITAKAITS OF TIIK HEDGEHOG (Erinaccus'). 



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

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

 pivputial glands ; Cd, Cowper's glands ; /'/; 7V 1 , the clillerent lobes of the 

 prostate; ,b'&, vesicula scmiualis ; Ho, testis; Ep, epididyinis ; I'd, }'d 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 may be at times again withdrawn into the abdomen (e.g. in 

 Uodriiti;i) ; this is ol't'cctcil by nn'ans of the cremaster muscle, 



