se; for the first have a great deal of cartilage, and the second,
at any rate, a portion of calcareous matter in their bones. It may,
therefore, be said that the bones of fishes form a kind of intermediate
substance between true bones and cartilages. The backbone extends
through the whole length of the body, and consists of vertebrae, strong
and thick towards the head, but weaker and more slender as it approaches
the tail. Each species has a determinate number of vertebrae, which are
increased in size in proportion with the body. The ribs are attached to
the processes of the vertebrae, and inclose the breast and abdomen. Some
kinds, as the rays, have no ribs; whilst others, as the sturgeon and
eel, have very short ones. Between the pointed processes of the
vertebrae are situated the bones which support the dorsal (back) and the
anal (below the tail) fins, which are connected with the processes by a
ligament. At the breast are the sternum or breastbone, clavicles or
collar-bones, and the scapulae or shoulder-blades, on which the
pectoral or breast fins are placed. The bones which support the ventral
or belly fins are called the _ossa pelvis_. Besides these principal
bones, there are often other smaller ones, placed between the muscles to
assist their motion.

206. SOME OF THE ORGANS OF SENSE IN FISHES are supposed to be possessed
by them in a high degree, and others much more imperfectly. Of the
latter kind are the senses of touch and taste, which are believed to be
very slightly developed. On the other hand, those of hearing, seeing,
and smelling, are ascertained to be acute, but the first in a lesser
degree than both the second and third. Their possession of an auditory
organ was long doubted, and even denied by some physiologists; but it
has been found placed on the sides of the skull, or in the cavity which
contains the brain. It occupies a position entirely distinct and
detached from the skull, and, in this respect, differs in the local
disposition of the same sense in birds and quadrupeds. In some fishes,
as in those of the ray kind, the organ is wholly encompassed by those
parts which contain the cavity of the skull; whilst in the cod and
salmon kind it is in the part within the skull. Its structure is, in
every way, much more simple than that of the same sense in those animals
which live entirely in the air; but there is no doubt that they have the
adaptation suitable to their condition. In some genera, as in the