IGUANOID GROUP. i 39 



the ground, and often stopping for a minute or two to doze with closed eyes, and 

 the hind-limbs stretched out on the arid soil. According to Darwin's account, 

 " they inhabit burrows, which they sometimes make between fragments of lava, 

 but more generally on level patches of the soft sandstone-like tufa. The holes do 

 not appear to be very deep, and they enter the ground at a small angle ; so that 

 when walking over these lizard-warrens, the soil is constantly giving way, much 

 to the annoyance of the tired walker. This animal, when making its burrow, 

 works alternately the opposite sides of its body. One front-leg for a short time 

 scratches up the soil, and throws it towards the hind-foot, which is well placed so 

 as to heave it beyond the mouth of the hole. That side of the body being tired, 

 the other takes up the task, and so on alternately .... They feed by day, and 

 do not wander far from their burrows ; if frightened, they rush to them with a 

 most awkward gait. Except when running downhill, they cannot move very 

 fast, apparently from the lateral position of their legs. They are not at all 

 timorous; when attentively watching anyone, they curl their tails, and, raising 

 themselves on their front-legs, nod their heads vertically, with a quick movement, 

 and try to look very fierce ; but in reality they are not so at all ; if one just stamps 

 on the ground, down go their tails, and off they shuffle as quickly as they can." 

 If worried with a stick, these lizards will bite it severely ; and when two are held 

 together on the ground, they will fight and bite till blood flows. " The individuals, 

 and they are the greater number, which inhabit the lower country, can scarcely 

 taste a drop of water throughout the year; but they consume much of the 

 succulent cactus, the branches of which are occasionally broken off by the wind. 

 I several times threw a piece to two or three of them when together ; and it was 

 amusing enough to see them trying to seize and carry it away in their mouths, 

 like so many hungry dogs with a bone." They also eat the leaves of several trees, 

 more especially of an acacia, to obtain which they ascend the low stunted trees, on 

 the boughs of which they may often be observed quietly feeding. The females lay 

 large eggs of an elongated form in their burrows ; both these and the flesh of the 

 lizards themselves being eaten by the inhabitants of the Galapagos. 



The true iguanas, of which there are two closely-allied species 

 True Iguanas. . . . . 



from Tropical America and the West Indies, differ from the two pre- 

 ceding genera in that the edges of the crowns of the cheek-teeth are serrated, while 

 the front teeth are simply conical. The distinctive features of the iguanas are to be 

 found in the long and much compressed body, the large four-sided head, covered above 

 with enlarged scales, the short neck, powerful limbs, long-toed feet, and the much 

 elongated tail, upon which the scales are uniform and keeled. The throat is 

 furnished with a large non-dilatable appendage, in front of which is a crest of large 

 compressed scales; and a continuous crest of long spines runs from the nape along 

 the back, and is continued as a ridge on the tail. The scales on the back are small, 

 equal, and keeled; the neck has some scattered large conical or bluntly -keeled 

 tubercles, and there are also some large tubercular scales on the sides of the throat, 

 more especially one below the aperture of the ear ; while on the under-parts tin- 

 scales are either smooth or slightly keeled. The pores on the thighs are numerous, 

 and, in addition to those in the margins of the jaws, there are teeth on the pterygoid 

 bones of the palate. The common iguana {Iguana tuberculata) attains a length 



