Further, there is the following diversity observable in wombs as compared with one another: namely that the females of horned animals which do not have teeth in both jaws are furnished with cotyledons in the womb when they are pregnant, and such is the case, among animals with teeth in both jaws, with the hare, the mouse, and the bat; whereas all other animals that have teeth in both jaws, and are viviparous and furnished with feet, have the womb quite smooth, and in their case the attachment of the embryo is to the womb itself and not to any cotyledon.