THE UROGENITAL SYSTEM. 267 



vesical pouch of the peritoneum, which Hes between the rectum 

 and the bladder. It holds the body of the uterus to the lateral 

 wall of this pouch, and together with the opposite ligament 

 and the body of the uterus forms thus a transverse partition, 

 which divides the rectovesical pouch into dorsal and ventral 

 portions. 



The round ligament (//) is a fibrous band which extends 

 from a point of the body wall, which corresponds exactly to 

 the internal inguinal ring of the male, to the cornu of the 

 uterus about two centimeters from the cranial end. It is 

 attached to the broad ligament by an intervening fold of 

 peritoneum. 



The Vagina {in). — The vagina extends from the os uteri 

 (at /) dorsad of the symphysis of the pelvis to a point a short 

 distance craniad of the caudal border of the ischiatic symphysis. 

 At this point it joins the neck of the bladder {k) to form the 

 vestibulum or urogenital sinus («), which is homologous with 

 the urethra of the male. 



Urogenital Sinus (n). — The urogenital sinus extends from 

 the caudal end of the vagina {in) to the external opening, 

 which is situated ventrad of the anal opening. It is about a 

 centimeter long and nearly as wide, and is marked off from 

 the vagina by a circular fold of mucosa, while its inner surface 

 presents longitudinal folds. On its ventral wall at its cranial 

 end is the opening of the neck of the bladder, which is 

 enclosed by a ring-like elevation of the mucosa, most prominent 

 at the sides. The external entrance to the urogenital sinus 

 forms the vulva. 



The Clitoris. — The clitoris is a minute organ homologous 

 with the penis and lying on the ventral floor of the urogenital 

 sinus. Its distal end lies at the entrance of the urogenital 

 sinus on its ventral border. In adult specimens the prepuce 

 of the clitoris appears as a slight elevation of the integument 

 surrounding a central vascular structure which appears red in 

 the fresh organ. From the clitoris there are two small cor- 

 pora cavernosa clitoridis {o) passing craniad and then diverging 

 to be attached to the ischiatic rami. The ischiatic portion of 



