830 
in reality they are distinct elements of the 
skull. In the higher Vertebrata they are con- 
solidated with the sphenoid, and have received 
the names of ale minores or apophyses ingrassii. 
Above these pass out the olfactory and beneath 
them the optic nerves, a circumstance which 
in itself sufficiently indicates their real nature. 
Sometimes, as in the Carp, they are united 
together inferiorly, so as to form a roof over 
the optic nerves. 
The ethmoid, Owen (anterior sphenoid, Cuv.: 
15,) so highly developed in the carnivorous 
Mammalia, is in the lower Vertebrata reduced 
to an extremely simple condition. In Fishes 
(fig. 437) it is generally distinct enough, form- 
ing the posterior boundary of the interorbital 
septum, but sometimes it is quite wanting or 
represented by membrane. When present, it is 
generally placed upon the sphenoid, sending 
off processes to join sometimes the ingrassial 
bones, sometimes the alar bones, or occasionally 
to remain suspended in the interorbital mem- 
brane that unites all these parts. The ethmoid 
appears to be deficient throughout all tribes of 
Reptiles. In Birds it is recognizable as a bone 
of considerable size, os tiga the posterior 
parts of the orbits, which it assists in forming 
the two lateral facets that enter into the com- 
position of those cavities corresponding with 
the ossa plana, as they are called, of the human 
subject; but these are obviously only portions 
of the ethmoid itself. In the Mammalia, 
owing to the prodigious developement of the 
olfactory apparatus, the e@thmoid becomes ex- 
tremely increased in size and importance, 
closing the anterior extremity of the cranial box, 
where it is perforated so as to present a central 
crest and cribriform plate, while inferiorly it 
has superadded to its body the superior tur- 
binated osseous lamelle that enter so largely into 
the construction of the olfactory organ. 
The vomer (16) is in Fishes a large and im- 
portant bone, joined posteriorly to the sphenoid 
and above to the @thmoid, forming a vertical 
portion, on each side of which are situated the 
organs of smell. Inferiorly it forms part of the 
roof of the mouth, and is often armed with teeth. 
Throughout all the Vertebrata this portion of the 
skeleton holds an analogous position and is re- 
cognized with facility. In Frogs and Lizards the 
bone is double, but in Tortoises and the higher 
animals generally there is but a single vomer, 
which enters more or less into the composition 
of the nasal septum. 
The nasal bones, Owen; (@thmoid, Cuv.: 
3) in Fishes are represented by a single bone 
impacted between the mid-frontals and the pre- 
frontals, and inferiorly joined to the vomer, 
forming a kind of septufh between the nasal 
organs, and thus in position resemble some- 
what the vertical lamella of the ethmoid of 
Mammalia. Sometimes, as in the Eel and the 
Conger, the bones in question are inseparably 
united into one piece. In the higher animals 
the nasal bones are two in number, covering 
the nasal cavity like an arch. They are present 
in all Reptiles except the Chelonians, and in 
Birds and Mammals are easily recognizable 
from their position. 
_Tumerous rows of teeth attached to its und 
OSSEOUS SYSTEM. (Comp. Anat.) 
The inferior turbinated bones, although in 
consequence of the construction of their nose 
quite wanting in Fishes, must not be omitted 
in enumerating the elements composing the 
skull in higher animals. In the humbler Rep- 
tiles, indeed, no traces of it are distinguishable ; 
but when the olfactory apparatus becomes fully 
developed, as in the Mammalia, they form an 
important part of the nasal character, and are 
found of large size, connected inseparably with 
the bones that surround the nose, 
The bones of the face have been already 
considered as constituting a very com { 
framework, destined to lodge the organs of the . 
principal senses or to constitute the instruments 
appropriated for the prehension or mastication 
of food. Seeing, however, that the same bone 
not unfrequently enters into the composition of 
several distinct cavities, we are unable to classify 
them further, and must therefore content our- 
selves with enumerating them seriatim as they — 
occur to our notice. , Y 
The maxillary (18) perform only a secon 
office in forming the upper jaw of a Fish, being 
in the finny tribes genera!ly destitute of teeth, — 
which in them are principally implanted upon 
the intermaxillary (17) that form the greater 
rtidn of the upper jaw. The maxillary in 
ishes is moveably articulated with the inter- 
maxillary, the vomer (16), and the palatine (22). 
Sometimes, as in the Herring and Lepisosteu: 
this bone is divided into several pieces. In 
Skates and Rays the whole upper jaw is made 
up of a single ossified mass, which bears the 
: 
surface. af 
But in all Reptiles, in Birds, and in Mam- 
malia the maxillary bones form the principé 
portion of the upper jaw, more particularly in 
the Mammalia, where the intermaxillary bone; 
are comparatively of small size. In this portio 
of the upper jaw are fixed the grinding teeth 
where such are present, a circumstance which 
in itself demands great strength in this part o 
the face; and, consequently, wherever powe 
of jaw is required to be conferred, it is prin 
apeny obtained by the increased developeme 
of this element of the skeleton, which thus 
comes the largest and, as it were, the cent 
bone of the whole fabric. 
The intermazillary bones (17) form the pri 
cipal part of the upper jaw in Fishes, and up 
their shape depends that of the snout. Se 
times these bones are flattened horizontally, 
compressed laterally, or prolonged into a be 
their form being modified by circumstan 
inalmost every genus. In the Chondroptery 
nevertheless, they are mere rudiments imbed 
in the substance of the upper lip. They 
persistent throughout all orders of Rept 
Birds, and Mammals, until we arrive 
Quadrumana, where they become anchyle 
with the maxillary, and in Man they are qi 
obliterated at an early period. ’ 
The bones of the face in osseous Fishes : 
exceedingly numerous and irregular, neith 
it easy to identify many of them as being at 
analogous to those which normally make 
the face, even of those Reptiles which pre 
- 
