958 
Fishes. It is only less abundant, and conse- 
quently the texture of the bone does not be- 
come so hard or homogeneous. 
It is very gratuitously that the skeleton 
of ordinary Fishes has been supposed to be 
more flexible, of a softer nature, and more ex- 
tensible than in the superior classes of Verte- 
brata. Most Fishes have their bones as hard 
as or harder than other animals, and there are 
even some, in the texture of which neither 
pores nor fibres are distinguishable, and which 
appear homogeneous or even vitreous to the 
e. 
No Fish, either osseous or cartilaginous, has 
a medullary canal in its bones; but there are, 
some, as the Trouts, in which the bony tissue is 
more or less penetrated with an oily fluid. 
There are some Fishes in which, whilst the 
rest of the skeleton acquires great hardness, 
some parts remain always cartilaginous, as for 
example, the head of the Pike. 
SKELETON oF ossEous FisuEs.—In osseous 
Fishes, we shall regard the skeleton as being 
composed of the head, of the respiratory appa- 
ratus, of the trunk, comprising the body and 
tail, and of the limbs, viz, the pectoral and 
ventral fins. The vertical fins, viz, those of the 
back, anus, and tail, may be regarded as form- 
sof oy of the trunk. 
e head having more moveable appendages 
than that of Quadrupeds must be divided into a 
greater number of regions. We may distinguish 
in it the cranium, the jaws, the bones placed un- 
der the cranium behind the jaws, serving for their 
suspension and motions; the opercular bones, 
forming flappers, which open and shut the 
openings of the branchie ; the bones surround- 
ing the nostril, which are nearly external, as 
also are those around the eye or the temple, or 
which cover a part of the cheek. 
The respiratory apparatus comprises the os 
hyoides and its appendages, that is to say, the 
branchiostegous rays and the arches supporting 
the branchiz, as also the different pieces at- 
tached to these arches, and which altogether 
rform the functions of larynx and of trachea ; 
lastly, the bones placed at the entrance to the 
pharynx, forming in some measure a second 
pair of jaws. 
The trunk is composed of the vertebre of the 
back and tail (for we can hardly say there is a 
neck, neither is there any sacrum,) of the ribs, 
of the bones called interspinous, which support 
the dorsal and anal fins ; also the rays of these 
fins, as well as of the tail. These rays, whether 
they have branches or articulations, or are 
simply spinous, are always divisible into two 
lateral halves. There is rarely a sternum, pro- 
rly so called, in Fishes; and when it exists, 
it is formed of pieces which are almost external, 
and which unite the lower extremities of the 
ribs. 
The anterior extremity or b origeee fin com- 
prehends the shoulder, which is an osseous 
semicircle composed of many bones, suspended 
at the upper part to the cranium or spine, and 
uniting inferiorly with its fellow of the opposite 
side. We may here find bones analogous to 
the two pieces of the scapula of Reptiles, to 
PISCES. 
the humerus and to the bones of the forearm ; 
there is even generally a process rage ees of 
two pieces protruding backwards, in which we 
might seek to see the coracoid bones and even 
the clavicle. 
The two bones comparable to the radius and 
ulna carry at their edge a row of ossicula, 
which appear to represent those of the carpus, 
and which support the rays of the proees fin, 
with the exception of the first, which articu- 
lates at once with the radial bone. 
The posterior extremity is much more va- 
riable in position than among Mammalia; its 
external or moveable portion, called the ventral 
Jin, emerges sometimes before, sometimes behind, 
and sometimes immediately beneath the an- 
terior extremity. The pelvis is composed of four 
bones, the largest and most constant of which, — 
being always in front of the anus and genital 
orifices, may be considered as a sort of pubis, 
and these carry on a part of thei post ae 
out interme-— 
the rays of the ventral fin, wi 
diate bones which can nd either to 
femur, tibia, fibula, or tarsus. The rays of the 
pectoral and ventral fins, as of those of the 
single ones, are divisible longitudinally into 
two portions. 
ertebral column.—The vertebre of a Fish 
are at once recognisable by the deep conical 
cavities which form the articulating surfaces 
whereby they are connected together, so that a 
double hollow cone always occupies the 
terval between two vertebre, which in th 
living state is filled up by a soft membrane 
and gelatinous substance, which ror 
One intervertebral cavity into another through 
holes which generally perforate the centres 
the bodies of the vertebre. ; 
In Fishes, as in all other animals, each ver- 
tebra presents superiorly a ring for the passage 
of the spinal medulla bounded by the superio 
spinal lamine ( neurapophyses ), which is gene 
rally surmounted by a long spinous proces 
(fig. 493, 4,) at the base of which are situatet 
both upon the anterior and posterior aspect litt 
eminences that correspond to the articulat 
processes of other Vertebrata; but most gen 
rally these processes only touch or slight 
overlap those of the neighbouring vertebi 
without their being connected ‘4 
articulating facets. Sometimes, indeed, th 
exist on one side of the vertebra and 
on the other, so that they have no corr 
pondents wherewith to articulate. The | 
nular of the first vertebra is freque 
separated from the body during the whole 
time of the Fish, but in the other vertebra 
such separation is visible. > 
In some families, as in the Murenide, 
of the anterior vertebre have a little ere 
vertical apophysis developed from beneatl 
body. Geer fates ro a portion of 
bodies of their vertebre soldered to 
this there are examples among the 
Fistularide, and SHuridee. 
Those vertebra which are situated above 
abdominal cavity have transverse processes 
veloped to a greater or less extent. These, 
some instances, as, for example, in t 
ase 
