Few animals, except the female of the human species, receive the male when pregnant. In only one or two species, and no more, does superfœtation ever take place.[1] Cases are to be found stated in the journals of physicians, and of others who have paid particular attention to the subject, in which twelve embryos[2] have been removed at a single abortion. When, however, but a very short time has intervened between two conceptions, the embryos both of them proceed to maturity; as was seen to be the case with Hercules and his brother Iphicles.[3] This was the case also with the woman who brought forth two children at a birth, one of whom bore a resemblance to her husband, and the other to her paramour. So too, with a female slave in Proconnesus,[4] who was delivered of two children at one birth, one of whom bore a strong resemblance to her master, and the other to her master's steward, with both of whom she had had connection on the same day; with another woman who was delivered of two children at a birth, the one after the usual period of gestation, the other an em- bryo only five months old: and again, with another female, who, having been delivered of one child at the end of seven months, in due course, two months afterwards, brought forth twins.[5]