Zoological Society. 495 



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. , , • i. r 



This crest or mane commences behind the head, with three or tour 

 excrescences of different sizes, then suddenly becomes, in larger Igua- 

 nas, an inch and a half or two inches in length, and runs umnter- 

 rup'tedly 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 eyehd ; 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 m the young and dirty grey 

 in the old Iguanas, with about six black streaks across the body and 

 fifteen across the tail, each streak being darker towards the head, and 

 gradually shaded off towards the tail. These streaks extend over the 

 dorsal and caudal crests, which partake entirely of the variegations 

 of the body in the younger, but, in the older mdividuals, are tipped 

 with red and yellowish brown at their bases and extremities. These 

 black streaks do not unite under the belly or under the anterior part 

 of the tail, but towards the extremity of the tail they gradually elon- 

 gate and become more dull, encircling the tail, and at last becoming 

 hardly discernible, mixing with the green or grey into one dull tint. 



The dewlap, as well as the folding skin in front of the shoulder, 

 connected with it, is mterspersed with black and yellowish brown, of 

 which colours the denticulations of the dewlap also partake. The 

 upper part of the head is of a darker and richer green in the young, 

 fading as the animal advances in years, and becomes veeather-beaten, 

 as is the case with the human species, and with all animal and vege- 

 table life. The whole of the under part of the body is of a lighter 

 colour in both old and young. The female has a more deUcate colour 

 and general appearance than the male. 



Whilst always retaining the same colours, this Iguana has the power 

 of considerably changing his hues, but these changes are gradually 

 performed. The colours become more dull as the period of the 

 chano-e of skin approaches, which is not, however, frequent. Each 

 scaleltias its own tint, and the colours being thus irregularly blended, 

 an appearance is given, particularly to the younger reptiles, very much 



