110 REPTILES AND BIRDS. 
pressed and covered with small imbricated and carinated scales. 
Messrs. Duméril and Bibron describe the genus, thus modified, as 
principally remarkable for the cutaneous prolongation which consti- 
tutes the deep and thin dew-lap, or pouch, the free border of which 
describes a curved line, and is dentated at the part nearest the chin. 
Fig. 27.—Common Iguana. 
The head is moderately long, and has the form of a pyramid with 
four faces. The neck is slightly compressed, the limbs long, the toes 
unequal and sometimes denticulate on the edge. The five toes of the 
posterior feet are graduated ; the tail, which is long and slender, is 
shghtly flattened from right to left. The Iguanas live chiefly on 
trees, but they take readily to the water, and swim with great facility. 
There are numerous species, all of which are found in South 
America and the Antilles. In the Island of Isabella, Sir E. Belcher 
