2*0 NATURAL HISTORY. 



A large Lizard with a beautiful green-coloured back, yellowish-green sides and belly, with 

 brown stripes or zigzags lined with yellow, and with its long tail ringed with green, yellow, and 

 brown, has a crest of tooth-like spines on the back and tail, a " bag " under the jaw, also crested, 

 long toes, and a rather compressed body. The head is moderately long, and has its top protected with 

 plates, and is raised between the eyes, and is more or less pyramidal in form. The neck is short, 

 and there is a fold of skin on it behind the " bag " which is reflected over the shoulders. 



This description applies to the large GREEN IGUANA,* which may be from three to five feet in 

 length. On looking at the mouth it is observed that the numerous teeth are fixed along the internal 

 face of the dentary bone, to which they adhere by one side of their bony root, and that they are 

 remarkable in shape. They are " pleurodont." They are rather long, compressed from side to side, 

 and are broad at the top, where they are angularly arched, pointed at the tip, and finely denticulate 

 on the slope on each side. The tympanic membrane is large and circular. 



These Iguanas live an arboreal life in tropical America and the West Indies, and are often 

 brought to Europe, and kept in zoological gardens and menageries. Climbing with ease and moving 

 with great rapidity amongst the foliage, they do not hesitate to take to water, the neighbourhood of 

 which they usually seek. They swim with ease, entering water voluntarily, and they do not then 

 use their fore limbs, but principally the tail. Brown, in his travels in. Guiana, noticed the Iguana on 

 the trees overhanging the rivers, and that they were greatly alarmed at the noise of the boat's paddles. 

 They threw themselves from the branches into the water, many coming down broadside on the surface. 

 Harmless things, they still will show fight, and the lash of their tail gives pain. Their food is not 

 -confined to vegetable diet, and as they have a row of teeth on the pterygoid bones, they can readily 

 capture and swallow small grubs and insects. Nevertheless, the insectivorous diet is the most usual, 

 although the blade-like serrate teeth are suited for biting leaves. 



The body of each vertebra is procoelous, that is to say, hollow in front and convex behind, the 

 hollow of one vertebra fitting into the convexity or ball of the one in front of it. The arch of bone 

 of each vertebra through which the spinal cord passes is attached to that of the vertebrae in front and 

 behind, by the ordinary oblique articular processes, which permit of a certain amount of motion of the 

 individual bone between its neighbours,! and of a general amount between all the vertebrae. In order 

 to prevent dislocation during rapidly complicated or contorted movements an additional structure is 

 provided, whose use, however, is not so apparent in the Iguana as it is in the Serpents. There 

 is a projection on the front of each arch which fits into a pit on the hind face of the preceding ai-ch,J 

 a peg-and-socket joint being formed. 



It is remarkable that in all the Iguanidae of the New World the teeth are pleurodont. But there 

 are others in which the teeth are acrodont, and their possessors ai-e inhabitants of the Old World, the 

 great Asiatic Islands, and Australia. The habits of all are much alike. 



A fine Cyclura lives in Cuba, which has a back crest, an extensible throat, and a very long com- 

 pressed tail with rings of spiny scales, and the Crested Anolis|| has the digits enlarged and united at 

 their base, and the throat sac is veiy extensible. It has none of the glandular structures in the fold 

 of the thigh which are seen in most of the groups. 



The most curious of all these American Iguanidse is called the BASiriSK,1T and might be taken 

 for an heraldic rather than a real and living active ti-ee Lizard. If it were twelve feet in length 

 instead of as many inches it would not be unlike a mediaeval Dragon without wings, and even in its 

 small development it looks very uncanny. Its broad and rather sharp-pointed scaly head has a 

 tall cap-like crest sticking up and back from the hinder part. A tall, thin, fin-like movable crest with 

 spines on it passes along the back, being highest over the loins, and there is a corresponding one 

 on the top of the long tail. The body is scaly and marked in zigzag. There is a very marked fold of 

 the skin on the throat, and the hind digits are fringed at their sides. It inhabits Central America. 



The genus AMBLYRHYNCHUS is represented in the Galapagos Islands, and the information about its 

 species is due to Charles Darwin, who writes in his celebrated Joiu-nal : "This Lizard** is 

 extremely common on all the islands throughout the Archipelago. It lives exclusively on the 



* Iguana tulerculata. t These articular processes are called Zygopophyses. 



J They are called Zygoxphcne and Zyrtantrum. Cydura carinatn. 



\\ Anolis occipitalia. ^ Bosiliwus mitratus. ** Ambl.i/rhynchus cristatus. 



