34 
OK THE PHYSIOOKOMY OF SEEPEKTS. 
anteriorly with the palatals, form with the latter two 
branches, most frequently in the form of an S, extending 
almost the whole length of the cranium. Their anterior 
extremity is either free or united to the vomer by ligaments, 
the posterior end is attached to the internal edge of the 
tympanite near its base. These bony slips, except in the 
Oligodon alone, are armed with teeth. Besides its union 
with the external pterygoid, the internal pterygoid is con- 
nected in many non- venomous serpents with the sphenoid. 
The same is the case with the palatals, which in all that 
tribe, and in all the true venomous snakes, are attached, 
by means of a small apophysis, to the base of the cranium. 
It remains that I describe the lower jaw. Everybody 
knows that its two branches are joined by a ligament at 
their anterior extremity, instead of being ankylosed. Each 
branch is composed of two principal parts, the dentiferous 
and the articular portions, of which the sutures are covered, 
on the internal face, by three little supernumerary bones ; 
the superior piece has been compared to the coronoid pro- 
cess in the skeleton of the mammifera ; but in many Ophi- 
dians, especially in the non- venomous serpents, the portion 
of which we now speak is almost reduced to nothing, and 
is placed under the dentiferous part ; whilst the true coro- 
noid process is well developed, and occupies the posterior 
part of the articular portion near its junction with the 
tympanites. The dentiferous part alone supporting the 
teeth is always bristled with them throughout its length ; 
it varies considerably in the different species, has acquired 
the greatest development in the Boa, and is least in the 
venomous snakes. It is superfluous to remark, that the 
development of the two principal portions of the lower jaw 
have an inverse ratio to each other, and that the extent of 
the whole of that jaw naturally augments with the size of 
its suspensory bones. These supporting bones occur as a 
pair on each side : Ist, The mastoid bone, attached to the 
cranium above the pars petrosa ; and, 2d, The drumsticks 
or tympanitic bones, ^ attached to the mastoids by ligaments, 
The bones are denominated in French les Caisses, or les Tympaniques. 
They have no analogy in the skeletons of mammifera, unless we consider 
them representing the upright angular portion of the lower jaw.] 
