The mole, on the other hand, possesses hair of the softest and most flexible description. In its subterranean galleries, which are not large enough to allow it to turn round, it must often be obliged to retreat backwards; and the hair therefore is so constructed as to lie equally smooth in every direction. This has been sup posed to be effected merely by its growing ex actly perpendicular to the surface of the body; but it is in fact still more effectually provided for by a remarkable form of the hair itself. Each hair consists of three or four broader portions connected by intervening portions of extreme tenuity; so that there are several points in the length of each hair which pre sent no appreciable resistance. The hair of the shrews is similarly constructed, and in each case it is to this structure that the pecu liar and beautiful softness which characterizes it is owing. It is worthy of remark that the colouring matter of the hair exists only in the broader portions, the intermediate parts being wholly colourless.
V. Organs of reproduction. — The repro ductive organs of the Insectivore offer, in several instances, some remarkable peculiari ties. The subterranean life of many of these animals renders the meeting of the sexes in their natural haunts a matter of almost for tuitous occurrence ; and it is therefore neces sary that the sexual desire should in the male be sufficiently powerful to force him as it were to seek and pursue the other sex through all the difficulties and disadvantages occasioned by their peculiar habits. Hence we find that in most of them the male organs are developed to an extraordinary degree; and in the mole the enlargement of the testes as the season of pairing advances is as remarkable as it is in the sparrow or in any other example of this sea sonal increase of those organs. Two incom patible statements have been made respecting the testes in the mole. Cuvier asserts that they make their appearance externally during the season of propagation. Illumenbach de clares that they belong to the true tcsticonda, with the hedgehog, &c. The truth is, as de monstrated with his usual ingenuity by Gcof roy St. 11 ilaire, that the testicles of the mole never make their appearance externally, al though during the season of their greatest de velopement they would do so but for the peculiar construction of the parts in which the organs of generation in this animal are con tained ; for the abdominal cavity extends be yond the pelvis, as far as the first four coccy geal vertebra', which in fact do not, properly speaking, in any degree constitute the tail, which is formed only of the posterior seven vertebra!, and the testes during the season are protruded so as to lie concealed under this portion of the caudal division of the spine, which forms as it were a continuation of the upper part of the pelvis. In the hedgehog the testes remain within the abdomen excepting during the spring, and even then they are but little protruded. The object of their being thus generally protected is obvious : in the hedgehog these organs, if external, would be exposed to danger from the act of rolling itself up, and in the mole and its congeners they would interfere with the act of excavating their subterranean passages. The penis in the
mole possesses a remarkable peculiarity, which doubtless has reference to the condition of the female organ presently to be described. It consists in a small terminal bony appendage, covered but slightly by integument; it was considered by Daubenton as the os penis, but from its different situation it may be doubtful perhaps if it be in truth analogous to that part.
The male organs are in the hedgehog deve loped to an extraordinary degree, more espe cially the vesieule seminales. The testes are of an oval form, smooth, and although large in proportion to the size of the animal, are much smaller than the vesiculm seminales; these are of enormous size, each consisting of four or five fascicles of extremely convoluted tubes, the membranous parietes of which are ex tremely thin and fragile. Cowper's glands and the prostatie gland are also of considerable size in this animal. The orifices of the rasa dcfe rentia, vcsicuhe seminales, prostatie gland, and Cowper's glands all open within the foramen ccccum of the urethra.
The female organs in the mole offer some peculiarities which deserve more attention than they have hitherto received.
In the first place, it appears that in this animal the urinary and genital orifices are wholly distinct. The clitoris, (fig. 455, c,) which is of considerable length, and very much resembles the penis of the male, is pierced for the passage of the urine, and thus constitutes a true urinary penis. l3cyond this is a trans verse slit of a slightly crescentic form, (fig. 455, 2), which constitutes the opening of the vagina. There are none of those duplicatures of the integument which in other Mammalia constitute the labia and nymphe, but the skin is smooth. But one of the most curious points in the structure of these parts is that in the virgin state this vaginal aperture does not exist, (fig. 455, 1,) the skin being per fectly and tightly drawn over the entrance; so that there are in this state but two openings, the urethral and the intestinal. So perfectly is this the case that it is very difficult to know a virgin female mole from the male by mere external examination. As this covering is so tense, the utility of the little bone at the extremity of the penis in the male is very obvious, and its pointed and tapering form is at once accounted for : it is clearly intended to perforate this tense covering to the vagina.
Another peculiarity in this animal is that the abdominal cavity being extended greatly be yond the pelvis, the vagina, the rectum, and the urinary passage terminate considerably fur ther back than in other animals. The opening of the rectum is opposite to the articulation of the fourth with the fifth caudal vertebra.
The uterus is of considerable size in the mole, and its cornua much convoluted.