The young enter into this pouch to suck, and soon acquire the habit of hiding themselves in it, so that they retire thither whenever they are frightened. This pouch opens and shuts according to the will of the animal; which it effects by several muscles and two bones, which are peculiar to the opossum; these two bones are about two inches in length, placed by the os pubis, they decrease gradually from the basis to the extremities, and support the muscles which open the pouch; the antagonists of these muscles serve to shut it so exactly, that in the living animal the opening cannot be seen, without forcibly dilating it with the fingers. The inside of this pouch is full of kernels, which contain a yellow substance, the smell of which is so offensive, that it infects the whole body of the animal; yet when this matter is dried, it not only loses its disagreeable smell, but acquires a perfume which may be compared to that of musk. This pouch is not, as Marcgrave and Piso have falsely asserted, the place in which the young are conceived; the female opossum has an internal womb, different indeed from that of other animals, but in which the young are conceived, and remain till they are brought forth. Tyson says, that in this animal there are two wombs, two vaginas, and four ovariums. M. Daubenton does not agree with Tyson in these particulars; but by his description, it is at least certain, that in the organs of generation of the opossums, there are several parts double which are single in other animals. The glans penis of the male, and the glans clitoridis in the female, which are forked, and seem double. The vagina, which is single at the entrance, is afterwards divided into two channels; this conformation is very singular, and differs from that of all other quadrupeds.