NATURAL HISTORY. 
104 
[n. zool. gal. 
dilated on tfte sides into a pear-shaped disk, so as to enable these ani¬ 
mals to walk on smooth and nearly perpendicular surfaces; of this 
genus there are many species. Lastly, the Marbled Lizards (Poly- 
chrus) have neither dilated toes nor any dorsal crest. 
Other broad-tongued Lizards have their teeth placed on the edge of 
the jaws, and so firmly fixed to them as to appear part of the jaws 
themselves; as the Chameleons and Agamse. They are only found 
in the warm parts of the Old World. 
The family of Agames ( Agamid^, Case 7) present several peculiari¬ 
ties of form, and have therefore been divided into many groups. Some 
have the head lyre-shaped, and the back and tail crested ( Gonyocepha- 
his) ; others have the head armed with spines over the back of the ears, 
and the scales large and directed upwards ( Calotes), which latter lay 
fusiform eggs. The Bronchoceles differ from the Calotes , by the scales 
of the back being small and horizontal; and the Acanthosaura has a 
square head and long subulate spines over the eyes. The true Agamae 
(Agama) have often bundles of spines on the sides of the neck. The 
maie Sitana has a large pouch under the throat, (which is quite want¬ 
ing in the female,) and they have no hinder thumb. The Stellio, 
which was formerly much esteemed for its supposed medicinal quali¬ 
ties, has bands of large spines round its tail. The Trapeli or Mutable 
Agamse, so called from the quickness with which they change the 
colour of their skin, are generally armed with irregular, spine-like 
scales. The Molochs of Australia are covered with long conical spines 
surrounded with small spines at their base. They are highly coloured, 
especially on the under side. The Earless Agamae ( Phrynocephali ) 
have the same irregular scales as the Mutable Agamae, but they differ 
from them and all the former, by the drum of their ears being hidden 
under the skin, as in the Chameleons. The Megalochilus differs from 
the former in the margin of the lips being spread out and fringed, and 
the claws very long. The Dragons ( Dracones ) differ from all these by 
the skin of the sides being spread out into the form of wings, and held 
up by the end of the ribs. The wings, when the animal is* at rest, are 
folded together on the sides of the body, butwdien it leaps from branch to 
branch they are spread out, and act as a parachute; there are several spe¬ 
cies, differing from each other in the length of the throat-pouches, and in 
the colour of the wings. The rest of the Agamidce are furnished with a 
series of minute glands on the under side of the hind legs; as the Gram- 
matophorce , peculiar to New T Holland, w 7 hich have rough scales like the 
Mutable Lizards, and the Lophyri have a crest of large scales on the back, 
which has caused them to be confounded with the Basilisks. Others 
with these glands, are peculiar 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 ( Chameleonidhs, Case 7) 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 
distance to which they can protrude the tongue, in order to catch in¬ 
sects, 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, 
