The exterior of the chorion is everywhere in contact with the uterine walls, and in shape repre sents exactly the interior of the - cornua uteri, upon which it is 1 moulded, the placenta occupying 1_ the greater portion of its extent.
, Mammary Glands.—It was ge - nerally believed from the time of e Aristotle until a very recent period, that in themale horse there were no nipples or other rudiments of the female mammm; except, as Aristotle expresses it, in such animals as resemble their mothers*: that is to say, in other words, that there were a few exceptional cases. Subsequent authors have stated the same concerning male solipeds in generalt, although none stated in what the resemblance consisted, or where the mammm in those furnished with them were situated ; so that even Buffon asserted it as a fact, that the male solipeds had no vestiges of mammm. Daubenton, however, having previously dis covered the situation of these organs in the male ass, was led from analogy to expect their presence in the horse likewise, and soon detected them, but situated in a very unusual position, — namely, upon the prepuce of the animal. The prepuce of the stallion is found to form a kind of prominent ring around the aperture through which the penis is protruded, and it is upon this circular protuberance, close to the sides of the scrotum, that the main mm are situated. These organs are two in number (fig.518.ff ), situated at a distance of about half an inch from each other, and are easily distinguishable from the circumstance of the skin being raised into a papilla around each nipple, in the centre of which there is a shallow depression. It would seem, however,
that in old horses the presence of these ru dimentary mamunm becomes less apparent.
In the mare, the mammary glands are situ ated between the thighs at a distance of about nine inches in front of the vulva. The nipples are only two in number, one on each side of' the mesial line, and their distance from each other is not more than an inch and a half. As in the goat and many herbivorous quadrupeds, all the lactiferous ducts form, in the base of each gland just above the root of the nipple, a large hollow cavity, which is divided by an internal septum into two chambers, one situ ated in front, and the other behind ; from each chamber a separate duct is derived, which passes along the nipple as far as its extremity, where it terminates. The orifices of these canals are situated, one behind, the other about a line, apart. It is owing to the presence of the reservoirs thus formed by the cavities of the mammary glands, that the lacteal secretion is permitted to accumulate in considerable quantities, until required for the nourishment of the young, or removed by human agency for the purpose of procuring the milk, which is frequently employed as an article of diet.