604 GENITAL ORGANS OF THE MARE 
The clitoris is the homologue of the penis and consists of similar parts (minus 
the urethra and its muscle). The corpus clitoridis is about two inches (ca. 5 em.) 
long, and its diameter about that of one’s little finger. It is attached to the ischial 
arch by two crura (Crura clitoridis). The glans clitoridis is the rounded and en- 
larged free end of the organ which was noted above as occupying the fossa clitoridis 
in the ventral commissure of the vulva. It is covered by a thin pigmented integu- 
ment, similar to and continuous with that which lines the fossa; these constitute 
the prepuce of the clitoris (Praeputium clitoridis). The organ is composed of erectile 
tissue similar to the corpus cavernosum penis. The ischio-cavernosus is the 
homologue of the muscle of the same name of the male; it is a very feeble muscle. 
The veins of the clitoris communicate by an intermediate plexus on either side with 
the bulbus vestibuli. 
THE FEMALE URETHRA 
The female urethra (Urethra feminina) represents only that part of the canal 
of the male which les between the internal urethral orifice and the colliculus semi- 
nalis. Its length is two to three inches (5-7.5 em.), and its lumen is sufficient to 
allow easily the introduction of the finger; it is, however, capable of remarkable 
dilatation if sufficient care and patience are exercised in the process. — It lies centrally 
on the pelvic floor, and is related dorsally to the vagina, to which it is in part at- 
tached. The external orifice is at the anterior end of the vulva, as described above. 
Structure.—The intrinsic muscular coat consists of external longitudinal and 
internal circular fibers; it is absent where the urethra is attached to the vagina. 
The mucous membrane is thrown into longitudinal folds when the canal is closed; 
it is highly elastic, and is covered with stratified epithelium. There is a rich sub- 
mucous network of veins, forming a sort of corpus cavernosum. 
The urethral muscle (M. compressor urethree) embraces the urethra and is 
continuous with the constrictor vestibuli. It is covered by a fibro-elastic membrane. 
THE MAMMARY GLANDS 
The mammary glands (Glandule lactifera) are modified cutaneous glands 
which are so closely associated functionally with the genital organs as to be con- 
sidered accessory to them. 
In the mare they are two in number, and are placed on either side of the median 
plane in the inguinal region. Each gland has the form of a very short, flattened 
cone, much compressed transversely, and having a flat medial surface. It consists 
of the glandular mass or body of the gland (Corpus mammie) and the papilla or 
teat (Papilla mammie). The base is related to the abdominal wall, to which it is 
attached by areolar tissue, which contains a venous plexus, the superficial inguinal 
lymph glands, and a variable amount of fat. The apex is constituted by the teat, 
which is also flattened transversely and varies in length from one to two inches 
(ca. 2.5 to 5 em.). Between the bases of the teats is the intermammary groove. 
On the apex of each teat there are usually two small orifices placed close together; 
these are the openings of the lactiferous ducts. 
Structure.—The skin covering the glands is thin, pigmented, chiefly hairless, 
and supplied with numerous large sebaceous and sweat glands. Under this are two 
layers of fascia, except on the teats. The superficial fascia presents no special 
features. The deep fascia consists of elastic tissue; centrally two lamine detached 
from the abdominal tunic descend on either side of the median plane, forming a 
septum between the two glands, and constituting their ligamentum suspensorium.' 
The gland substance or parenchyma is pinkish gray in color, and of firmer 
LThese lamin are separated almost completely by a layer of areolar tissue, so that it is pos 
sible to remove a diseased gland by careful dissection between the layers of the septum. 
