34 Veterinary Obstetrics 



contraction, they produce a constriction on the vulvo-vaginal 

 border line. 



The mucous membrane, continuous with that of the urinary 

 bladder and the vagina, is covered with squamous epithelium 

 and contains numerous mucous glands, which are largely dis- 

 placed near the labial margins and about the clitoris by sebace- 

 ous follicles, the secretions from which are odoriferous, especially 

 during estrual periods, when the odor becomes very marked in a 

 manner characteristic of the species. 



Within the vulvar cavity are to be noted the meatus urinarius, 

 clitoris and vaginal bulb. The meatus urinarius, or terminal 

 opening of the urethra, is located along the floor of the vulva at 

 a distance of three to four inches from the external opening in 

 the mare. The urethral canal passes obliquely downwards and 

 forwards through the vaginal floor to the urinary bladder. In 

 most animals, the meatus urinarius is comparatively small and 

 inextensible while, in the mare, in general harmony with the 

 large and freely dilatable os uteri and genital passage, it is quite 

 ample. One, two or more fingers are readily passed through it 

 into the bladder and it is not rare to find the opening, in heavy, 

 lymphatic animals, sufficiently large to admit, without great diffi- 

 culty, the entire hand. The dimensions of the meatus urinarius 

 in the mare are of special significance clinically as they favor 

 eversion and prolapse of the bladder, an accident not particularly 

 rare in this animal, while extremely so in others. In the cow 

 the narrow meatus urinarius is further guarded by a valvular 

 membranous fold directed from the posterior border forward in a 

 manner, it is claimed, to prevent the penis of the bull from acci- 

 dentally entering it and wounding the bladder as a result of the 

 violent copulative thrust of that animal. Neverthele,ss we have 

 one instance recorded (see under " Accidents of Coition " ) in 

 which a fatal rupture of the bladder was caused in copulation. 



The clitoris is an erectile organ, analogous to the male penis 

 and having in general the same tissues, form and attachments. 

 It is two or three inches in length and arises, like the penis, by 

 two crura from the ischial arch and {)asses upwards and back- 

 wards to protrude from the vulvar floor just inside the inferior 

 commissure and is the principal element in maintaining the form 

 of this part. 



