Cartilaginous fishes come out from the main seas and deep waters
towards the shore and there bring forth their young, and they do so
for the sake of warmth and by way of protection for their young.

Observations would lead to the general rule that no one
variety of fish pairs with another variety. The angel-fish, however,
and the batus or skate appear to pair with one another; for there is a
fish called the rhinobatus, with the head and front parts of the skate
and the after parts of the rhine or angel-fish, just as though it were
made up of both fishes together.

Sharks then and their congeners, as the fox-shark and the
dog-fish, and the flat fishes, such as the electric ray, the ray,
the smooth skate, and the trygon, are first oviparous and then
viviparous in the way above mentioned, (as are also the saw-fish and
the ox-ray.)


The dolphin, the whale, and all the rest of the Cetacea, all, that
is to say, that are provided with a blow-hole instead of gills, are
viviparous. That is to say, no one of all these fishes is ever seen to
be supplied with eggs, but directly with an embryo from whose
differentiation comes the fish, just as in the case of mankind and the
viviparous quadrupeds.