MAMMARY GLANDS. 



navicularis. The length of the perineum is measured from the posterior 

 commissure to the margin of the anus, and is usually not more than an 

 inch. The external surface of the labia is covered with hairs ; the inner 

 surface is smooth, and lined by mucous membrane, which contains a num- 

 ber of sebiparous follicles, and is covered by a thin cuticular epithelium. 

 The use of the labia majora is to favour the extension of the vulva during 

 parturition ; for, in the passage of the head of the foetus, the labia are un- 

 folded and completely effaced. 



The Labia minora, or nymphce, are two smaller folds, situated within 

 the labia majora. Superiorly they are divided into two processes, which 

 surround the glans clitoridis, the superior fold forming the praeputium cli- 

 toridis, and the inferior its frsenulum. Inferiorly, they diminish gradually 

 in size, and are lost on the sides of the opening of the vagina. The 

 nymphce consist of mucous membrane, covered by a thin cuticular epi- 

 thelium. They are provided with a number of sebiparous follicles, and 

 contain, in their interior, a layer of erectile tissue. 



The Clitoris is a small elongated organ situated in front of the ossa 

 pubis, and supported by a suspensory ligament. It is formed by a small 

 body, which is analogous to the corpus cavernosum of the penis, and, like 

 it, arises from the ramus of the os pubis and ischium on each side, by two 

 crura. The extremity of the clitoris is called its glans. It is composed 

 of erectile tissue, enclosed in a dense layer of fibrous membrane, and is 

 susceptible of erection. Like the penis, it is provided with two small 

 muscles, the erector es clitoridis. 



At about an inch behind the clitoris is the entrance of the vagina, an el- 

 liptical opening, marked by a prominent margin. The entrance to the 

 vagina is closed in the virgin by a membrane of a semilunar form, which 

 is stretched across the opening ; this is the hymen. Sometimes the mem- 

 brane forms a complete septum, and gives rise to great inconvenience by 

 preventing the escape of the menstrual effusion. It is then called an im- 

 perf orate hymen. The hymen must not be considered a necessary accom- 

 paniment of virginity, for its existence is very uncertain. When present, 

 it assumes a variety of appearances : it may be a membranous fringe, with 

 a round opening in the centre, or a semilunar fold, leaving an opening in 

 front ; or a transverse septum, having an opening both in front and be- 

 hind ; or a vertical band with an opening at either side. 



The rupture of the hymen, or its rudimentary existence, gives rise to 

 the appearance of a fringe of papillae around the opening of the vagina; 

 these are called carunculce myrtiformes. 



The triangular smooth surface between the clitoris and the entrance of 

 the vagina, which is bounded on each side by the upper portions of the 

 nymphse, is the vestibule. 



At the upper angle of the vagina is an elevation formed by the promi- 

 nence of fte upper wall of the canal, and analogous to the bulb of the 

 urethra of the male ; and immediately in front of this tubercle, and sur- 

 rounded by it, is the opening of the urethra, the meatus urinarius. 



MAMMARY GLANDS. 



The Mammae are situated in the pectoral region, and are separated from 

 the pectoralis major muscle by a thin layer of superficial fascia. They 

 exist in the male as well as in the female, but in a rudimentary state, 



