The striking singularities remarked by M. Sarrasin, in this animal are, first, the muscular force and great expansibility in the skin, which enables the animal to contract and compress its body into a smaller size. Secondly, the suppleness of the false ribs, which admits a contraction of body so considerable that the musk-rat can obtain an easy passage through holes where smaller animals cannot find admission. Thirdly, the manner in which the female voids her urine, the urethra not terminating, as in other animals, under the clitoris, but at a hairy eminence above the os pubis, and in which there is an orifice, that serves the urine to escape. This strange organization is found in only a few species of animals, as rats and apes have three apertures; and these two are perhaps the only animals who have a passage for the urine distinct from the organs of generation: to the females alone, however, does this singularity belong, for the conformation of the males is the same with that of other quadrupeds. M. Sarrasin observes, fourthly, that the testicles which, as in other rats, are situated on each side of the anus, become exceedingly large, considering the size of the animal, during the rutting season; but that over, they not only change in size, consistency, and colour, but even in situation, and with the seminal vessels, and all the organs of generation become almost invisible. And, lastly, that the vessels which contain the musk, or perfume, of this animal, under the form of a milky humor, and which adjoin the parts of generation, undergo the same changes; that during the rutting season they enlarge in a great degree, and then the perfume is exceedingly strong, and may be sensibly distinguished at a considerable distance, but at its expiration they become wrinkled, decay, and at length entirely disappear. The change in the vessels, which contain the perfume, is effected more quickly, and more completely, than that of the parts of generation. These vessels are common to both sexes, and at the above periods contain a considerable quantity of milky humor; and the secretion is formed, and the humor voided, nearly in the same place as the urine of other quadrupeds. These singularities were worthy the attention of so able an anatomist as M. Sarrasin. We have already mentioned similar alterations in the parts of generation in the water-rat, the campagnol, and the mole; but this is not the place for us to enlarge on the general consequences which might be drawn from these singular facts, nor even on the immediate references they may have to our theory of generation. These we shall soon have occasion to present with more advantage, by uniting them with other facts to which they relate.