The dolphin bears one at a time generally, but occasionally two.
The whale bears one or at the most two, generally two. The porpoise in
this respect resembles the dolphin, and, by the way, it is in form
like a little dolphin, and is found in the Euxine; it differs,
however, from the dolphin as being less in size and broader in the
back; its colour is leaden-black. Many people are of opinion that
the porpoise is a variety of the dolphin.

All creatures that have a blow-hole respire and inspire, for
they are provided with lungs. The dolphin has been seen asleep with
his nose above water, and when asleep he snores.

The dolphin and the porpoise are provided with milk, and
suckle their young. They also take their young, when small, inside
them. The young of the dolphin grow rapidly, being full grown at ten
years of age. Its period of gestation is ten months. It brings forth
its young summer, and never at any other season; (and, singularly
enough, under the Dogstar it disappears for about thirty days). Its
young accompany it for a considerable period; and, in fact, the
creature is remarkable for the strength of its parental affection.
It lives for many years; some are known to have lived for more than
twenty-five, and some for thirty years; the fact is fishermen nick
their tails sometimes and set them adrift again, and by this expedient
their ages are ascertained.

The seal is an amphibious animal: that is to say, it cannot take
in water, but breathes and sleeps and brings forth on dry land-only
close to the shore-as being an animal furnished with feet; it
spends, however, the greater part of its time in the sea and derives
its food from it, so that it must be classed in the category of marine
animals. It is viviparous by immediate conception and brings forth its
young alive, and exhibits an after-birth and all else just like a ewe.
It bears one or two at a time, and three at the most. It has two
teats, and suckles its young like a quadruped.

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.

At the breeding season the sperm-ducts of the male are filled with
sperm, so much so that if they be squeezed the sperm flows out
spontaneously as a white fluid; the ducts are bifurcate, and start
from the midriff and the great vein. About this period the sperm-ducts
of the male are quite distinct (from the womb of the female) but at
any other than the actual breeding time their distinctness is not
obvious to a non-expert. The fact is that in certain fishes at certain
times these organs are imperceptible, as was stated regarding the
testicles of birds.

Among other distinctions observed between the thoric ducts and the
womb-ducts is the circumstance that the thoric ducts are attached to
the loins, while the womb-ducts move about freely and are attached
by a thin membrane. The particulars regarding the thoric ducts may
be studied by a reference to the diagrams in my treatise on Anatomy.

Cartilaginous fishes are capable of superfoetation, and their
period of gestation is six months at the longest. The so-called starry
dogfish bears young the most frequently; in other words it bears twice
a month. The breeding season is in the month of Maemacterion. The
dog-fish as a general rule bear twice in the year, with the
exception of the little dog-fish, which bears only once a year. Some
of them bring forth in the springtime. The rhine, or angel-fish, bears
its first brood in the springtime, and its second in the autumn, about
the winter setting of the Pleiads; the second brood is the stronger of
the two. The electric ray brings forth in the late autumn.