32 
ON THE PHYSIOGNOMY OF SEKPENTS. 
cipital foramen are the largest. The entrance to that 
cavity is protected above by an osseous plate like a scale, 
salient and vaulted ; below projects the occipital condyle, 
supported by a neck, and composed of three pieces, which 
become one by age, forming a single plane, sometimes in 
the form of a trefoil, sometimes of a heart. 
5. We come, finally, to the temporals^ all around im- 
bedded between the occipitals and the parietals, and con- 
taining in their cavities the organs of hearing ; the back 
part contains the pars petrosa. 
The assemblage of the bones of the face are in the same 
plane with those that form the bony case of the true cra- 
nium ; and we shall now describe them. We observe, first, 
the anterior frontals, a pair of bones usually triangular, 
which determine the lateral portions of the face, and by 
their posterior portions assist in forming the anterior part 
of the orbit ; the inferior surface of this bone extends to the 
maxillary, with which it is articulated in the true venom- 
ous snakes ; its form and its direction vary exceedingly, 
according to the functions it has to perform, and its volume 
is reduced in the latter class of animals to a very small 
size. Finally, the internal surface composes the back part 
of the nasal cavity, of which, however, the principal part 
is formed by several bones attached by ligaments to the 
cranium, and allowing a certain degree of motion in a ver- 
tical direction. The pieces which also form the base of 
the snout, receive at this anterior end the intermaxillary : 
They are, 1st, the vomer, composed of two symmetrical 
pieces, united by their internal faces, broad and triangular 
before, slender towards the extremity which unites them to 
the sphenoid ; 2d, the nasals, almost always triangular, and 
with an anterior plate descending to form the septum which 
divides the nostrils ; they cover the nasal cavity ; 3d, a 
small bone analogous to the turbinated bones. 
We perceive, moreover, in the skull of Ophidians several 
supernumerary pieces, which, however, by ho means occur 
in every species. The first are the posterior frontals, bones 
which descend from the summit of the front to defend the 
posterior border of the eye. In the Trigonocephalus, the 
Crotalus, and in some serpents not venomous, we find only 
