OF THE OPHIDIAI^S IN OEKERAIi. 
25 
to the Ophidians ; the last traces appear in the Anguis 
and Acontias, and totally disappear in the Amphisbaena 
and the Typhlops. The simple suspensory hones of the 
jaw, the tympanites of serpents, replaced in most of the 
Saurians by two pieces, are found in the Acontias, although 
they are wanting in the Amphisbaena and the Typhlops. 
The whole bones of the cranium would perhaps furnish 
better marks of distinction between the two allied orders, 
if some species of the family of Typhlops, the Uropeltis, did 
not, in this respect, approach the Ophidians. It is well, 
however, to obtain an idea of the principal differences which 
distinguish the skulls of Saurians from those of Serpents. 
The bones of the face of the latter never form an immove- 
able mass, perforated by the nostrils, and composed of 
pieces let into each other ; as we observe in Saurians. In 
Ophidians, the intermaxillary bone of a compressed trian- 
gular form, is always free, mobile, and never united to the 
maxillaries by means of sutures ; the latter bones, when 
they are intimately united to the anterior frontals, present 
only a narrow attachment, and always possess some degree 
of mobility ; and the lateral edges of the nasal bones are 
always free through their whole extent. The Pterygoids 
constantly present themselves in the form of thin, slender 
bones, rather broad, and joined to the cranium by liga- 
ments, which readily yield to the movements, more or less 
extensive, which these parts are capable of performing. 
No Ophidian has a mouth armed with large conical teeth, 
perpendicularly implanted ; the organs in serpents, on the 
contrary, resemble hooks bent backw ards, with sharp points ; 
besides, serpents, with the single exception of the Oligodon, 
have the palate furnished with teeth like those of the jaws, 
whilst we find among the Saurians only traces of palatal 
teeth, in the form of minute irregular asperities. 
It may be seen, from all we have said on the structure 
of Ophidians, that these reptiles are especially remarkable 
for their mode of locomotion, and the manner of swallow- 
ing their prey. These are the circumstances which modify 
their whole structure : the first determines the general form 
of their bodies ; the second, that of their internal parts. 
We observe, on examining the general position of their in- 
c 
