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itself. Of the fore-legs the third and fourth toes are the longest ; 
and of the hind-legs the fourth toe is of an enormous length, and has 
five joints. Under the toes the scales form a double row of denticu- 
lations. The nostrils are large, oval, and not mobile, and above them 
are two horns, with five or six tuberculous excrescences between them 
and the nostrils, and surrounding the horns. The mouth is large, 
and armed with two rows of maxillary and two of palatal teeth, which 
appear simply to be intended to crop leaves and to provide the sto- 
mach with vegetable food. Each maxillary tooth is a little double- 
edged saw, and they are so lapped over each other that the reptile, 
in closing its mouth upon a leaf, cuts through it completely. The 
tongue is divided at the point, is very wide, and can be extended out 
of the mouth, although it is fastened to the interior of the lower jaw 
near its extremity. ‘The tongue is curiously used by the animal to 
draw food into the mouth, and to forward it down the gullet, or to 
repel it at will, and the only use of the palatal teeth appears to be to 
secure the food while the tongue moves forward to afford fresh assist- 
ance in its journey down the throat*. Between the lower jaw and 
the chest is a pouch, which the animal draws in or extends simulta- 
neously with the compression or swelling out of the body when en- 
raged or excited. The portion of the gular pouch attached to the 
jaw is inflatable, and food is sometimes retained im it for a consider- 
able period, but the lower part is merely extensible. On the anterior 
part of this pouch or dewlap, and immediately below the jaw, are 
from five to seven denticulations similar in substance and colour to 
the dorsal crest, but not so long. 
This crest or mane commences behind the head, with three or four 
excrescences of different sizes, then suddenly becomes, in larger Igua- 
nas, an inch and a half or two inches in Jength, and runs uninter- 
ruptedly down the back and tail, gradually diminishing, excepting 
above the commencement of the tail, where a slight increase again 
takes place, until, at the extremity of the tail, it is undistinguishable. 
The dorsal crest consists of about fifty protuberances, and the caudal 
crest of about 218, each of the latter becoming gradually harder as 
they decrease in height, and so altering their shape as to resemble, 
down the greater part of the tail, the edge of a saw. 
The ear is covered by a thin scale, which gives to the touch, but 
does not seem sensitive. There is no external opening, nor does the 
sense of hearing appear to be very acute or much used by the animal, 
who trusts more to the eye to discover both his food and his enemies. 
The eye is bright. and prominent, and is protected by an inner 
cuticle as well as the lower eyelid; the upper lid not moving to aid 
in covering it, but only when the direction of sight is altered in a 
perpendicular direction. There are soft brows over the eyes of a 
spherical shape, and projecting above the remainder of the upper part 
of the head. 
The general colour is bright green in the young and dirty grey 
in the old Iguanas, with about six black streaks across the body and 
* The tongue is always covered by a glutinous secretion, which is perceptibly 
appended to the jaws when the mouth is open. 
