3. The embryo and the ovum are enclosed in a common membrane, and beneath this there is another membrane, in which the embryo alone is enclosed. Between these membranes there is a fluid substance. The nutriment contained in the stomach of the young fish is similar to that in the young birds, partly white, and partly yellow. The form of the uterus must be learned from dissection. This organ is different in different fish, as in the galeode by themselves, and the flat fish by themselves: for in some the ova are attached near the spine to the centre of the uterus, as I observed before, as in scylia.[202] They descend when they begin to increase, when the uterus is double, and are attached to the diaphragm, as in other fish: the ova descend into each division.
4. The uterus of these fish, and of the other galeode, has a small appendage attached to the diaphragm like a white nipple, which is not present unless they are pregnant. The scylia and the batis have a shell-like substance, which contains the fluid of the ovum. In form the shell resembles the tongue of a wind instrument, and hair-like passages are attached to the shells. The young of the scylia, which some persons call nebria galei, are born when the shell falls off and bursts. The young of the batis when they are brought forth are excluded by the rupture of the shell. In the acantheas[203] galeos the ova are attached to the diaphragm above the nipples; and when the ovum descends, the young is attached to it after it is set free. The reproduction of the alopex is in the same manner.
5. Most galei which are called smooth have the ova placed between the divisions of the uterus, like those of the scylia; and as they surround it, they descend into each division of the uterus, and they are produced, attached to the uterus by an umbilical cord; so that when the ova are taken out, they appear similar to the embryo of quadrupeds. And the long umbilical cord is attached to the lower part of the uterus, each part, as it were, attached to an acetabulum; and to the middle of the embryo near the liver. And when it is dissected, the food is like an egg, though the ovum be no longer there. There is a chorion, and peculiar membranes surrounding each of the embryos, as in quadrupeds.