EXTERNAL GEiXERATIVE ORGANS. 29 



Inwardly, this muscle is in relation with the vaginal bulb and mucous 

 membrane of the vulva. Its external face is separated from the skin of 

 the lips by a very vascular cellulo-fibrous tissue, which is capable of con- 

 tracting, and in the midst of which ape observed some isolated red mus- 

 cular fasciculi — given off from the principal muscle. 



The posterior constrictor of the vulva is very powerful, and in acting 

 during copulation, contracts the vagina and compresses the penis ; by 

 reason of its attachment to the clitoris, when its acts it erects that organ. 

 In Mares which are rutting, the movements of the clitoris are frequent, 

 and it then projects outwards ; this is particularly observed after micturi- 

 tion, and in this case the fibres of the constrictor attached to the clitoris 

 elevate the latter by acting on its base, those fibres which are inserted 

 into the skin of the thighs depressing the inferior commissure of the vulva, 

 which exposes that very sensitive erectile body lodged in this space. 



The muscular ligaments of the vulva in reality correspond to the liga- 

 mentum suspensorium of the penis in the male ; they arise from the lower 

 face of the sacrum, and descend as flat bands until they unite beneath 

 the rectum, when they pass in several fasciculi into the lips of this part, 

 and mix wdth the fibres of the posterior constrictor. They are composed 

 of non-striated fibres. The skin, as already mentioned, is very fine and 

 thin, black in the great majority of Mares, has scarcely any hair, and is 

 very unctuous, odorous, and elastic. The bulk of the vulva is made up 

 of subcutaneous y<7J"«'^, to which the skin closely adheres ; as well as adi- 

 pose and connective tissue, and blood-vessels and nerves. 



The clitoris is an exact, but miniature, counterpart of the corpus caver- 

 nosum of the male penis. From two to three inches in length, this body 

 commences by two roots attached to the ischial arch, and which are cov- 

 ered by a rudimentary ischio-cavernous muscle. After being fixed to the 

 ischial symphysis, by means of a suspensory ligament similar to that of 

 the male, it passes backward and projects into the vulvular cavity, towards 

 the inferior commissure, in which it is lodged. Its free extremity is en- 

 veloped in a mucous cap — the preputium, which is plicated in different 

 directions ; and towards the centre of the tubercle is a follicular cavity 

 containing sebaceous matter, and which represents that in the extremity 

 of the male penis. In every respect the clitoris resembles that organ, 

 having a fibrous framework, erectile tissue, cavernous vessels or " plexus 

 retiformis," and a pair of muscles — the erectores clitoridis. This organ is 

 more especially the seat of venereal excitation during coition. It is pres- 

 ent in all the domesticated female animals, and is frequently erected 

 while they are in "heat," as well as in the act of copulation. It is 

 abundantly supplied with nerves, which endow it with most acute sensi- 

 bility, and the mucuous membrane enveloping it is usually dark colored 

 or marbled, though in white horses it may be colorless. 



The meatus urinarius is the orifice of the urethra, which is a very short 

 canal in the female. This canal passes immediately beneath the anterior 

 sphincter muscle of the vulva, and after a brief course (about two inches) 

 in the textures composing the floor of the vagina, opens into the vulvular 

 cavity at from four to six inches from its exterior. This opening, which 

 is on the floor of the cavity, is covered by a wide duplicature of the lin- 

 ing membrane that acts as, and is designated, the valve of the meatus or 

 vagina {yalvula vagi?ice) ; its free border is turned backwards, and it would 

 thus appear to direct the urine towards the external opening of the vulva, 

 and prevent its reflux into the vagina. Rainard states that this valve is 



