34 
NATURAL HISTORY. [UPPER FLOOR. 
The family of Chameleons (Chameleonidce, Case 4) 
have been long celebrated on account of the rapidity with 
which they change their colour; but most of the other 
Saurian Reptiles have the same faculty* and many in as 
great a degree. They are remarkable for the great dis¬ 
tance to which they can protrude the tongue* in order to 
catch insects* which form their principal food. They are 
only found in the warm parts of the Old World* and the 
species are chiefly distinguished from each other by the 
form of the head. In the common Chameleon* the occiput 
is arched and compressed* whilst* in the Senegal species, 
it is flat; some of the species, as the Eared and Hooded 
Chameleons* have the back part of the occiput furnished 
with two fleshy lobes ; whilst the Panther and Cape Cha¬ 
meleons have the front of the chin furnished with fleshy 
processes. Others have the head armed with horns* which 
in some are placed over the eye-brow* as in Brookes's Cha¬ 
meleon* in others on the tip of the nose* as in the Two¬ 
horned Chameleon* in others on the forehead* as in the 
Three-horned Chameleon. 
The Serpents ( Ophidia * Cases 6—13) are destitute 
of any limbs* or have them only in the form of short spurs on 
the side of the vent. Their mouths are capable of very 
extraordinary dilatation* in consequence of the bones of 
the jaw being separate from each other* to enable them 
to swallow very large bodies entire. 
The pre-eminently poisonous serpents* ( Venenosa * Case 6) 
have their upper jaws furnished with large* moveable fangs* 
having a small groove on the outer convex edge* for convey¬ 
ing the poison, secreted by a large gland situated under the 
eye* into the wound occasioned by the bite of the reptile. 
The fangs* when at rest, are concealed by a fold in the 
gums, and behind them are the rudiments of other fangs, to 
replace the former* if lost. The maxillary bones are small 
and carry only the fangs* but there are two rows of pala¬ 
tine teeth* in the upper part of the mouth. They are also 
generally distinguished by the large size of the head* which 
is only covered with small scales; by the scales of the 
body being usually rough and carinated* and by the tail 
being very short* and* in most instances* thin in compa¬ 
rison with the body. Their belly is covered with broad 
