35 
CHAPTER II. 
OPHIDIAN REPTILES, OR TRUE SNAKES. 
REPTILES are, as has been said in the preceding chapter, verte- 
brated animals, breathing by lungs, having red and cold blood— 
that is to say, not producing sufficient heat to render their tem- 
perature superior to that of the atmosphere; destitute of hairs, 
of feathers, of mammary glands, and having bodies covered with 
scales. 
Snakes, properly so called, have the tympanic bone, or pedicle 
of the lower jaw, movable, and nearly always suspended to another 
bone analogous to the mastoid bone, which is attached to the cra- 
nium by muscles and ligaments, a conformation which gives to these 
animals the vast power of distension they possess. ‘Their trachea 
is long, their hearts placed far back, and the greater number have 
one very long lung and vestiges of a second. They are divided 
into non-venomous and venomous; and the latter are sub-divided 
into venomous with maxillary teeth, and venomous with isolated 
fangs. 
The Snakes prey almost exclusively on animals of their own 
killing ; the more typical species attacking such as are frequently 
larger than themselves, and the maxillary apparatus is, as we 
have seen, modified so as to permit of the requisite distension. 
According to Professor Owen’s clear and intelligible description, 
the two superior maxillary bones have their anterior extremities 
joined by an elastic and yielding fibrous tissue with the small and 
single intermaxillary bone; the lower maxillary rami are similarly 
connected. ‘The opposite extremity of each ramus is articulated to 
a long and movable vertical pedicle formed by the tympanic bone, 
which is itself attached to the extremity of a horizontal pedicle 
formed by the mastoid bong, so connected as to allow of a certain 
yielding movement upon the cranium. The other bones have 
similar loose movable articulations, which concur in yielding to 
the pressure of large bodies with which the teeth have grappled. 
