ROOM X.] NATURAL HISTORY. 31 
ed with the Basilisks. Others with these glands, are pe¬ 
culiar for having the tail surrounded with rings of scales. 
In Uromastyx, the scales of the tail are large and spinous; 
in Leiolepis they are small and smooth. 
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 
wattles. 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 without 
any limbs, or have them only in the form of short spurs on 
the side of the vent. Their mouths are capable of being 
opened very widely, in consequence of the bones of the 
jaws being separate from each other, to enable them to 
swallow very large bodies entire. 
The most deadly 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 placed under the 
eye, into the wound occasioned by the bite of the reptile. 
The fangs, when at rest, are hid by a fold in the gums, 
and behind them are the rudiments of other fangs, to re¬ 
place 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 
