REPTILIA 253 



The largest American lizard is Iguana tuberculata (Fig. 138, D), a 

 native of South and Central America. The Iguana reaches a length 

 of five or six feet. Its habits are much like those of the Basilisk. 



Sub-order 3. Chamaeleontes (Chameleons). — The chameleons 

 are the most highly specialized of the lizards. The body is laterally 

 compressed, the tail prehensile, the toes are parted in the middle into 

 two groups used for grasping, a group of three being opposed by a 

 group of two. Most of them are African or Madagascan, though one 

 species (Chamceleon mdgaris) extends into Southern Europe. 



As an example of extreme arboreal specialization the group is of un- 

 usual interest. Two characters of chameleons have become noto- 

 rious: their ability to change color and their habit of "shooting" in- 

 sects with their tongues. Accounts of their color versatility are 

 exaggerated, but the fact remains that they ate probably the most ef- 

 fective color changers known, having a range from very light gray 

 to leaf green; and the change can be made in a few seconds. The 

 tongue is capable of "shooting" a fly at a distance of seven inches 

 and the aim is unerring. Probably the aim is improved by the cu- 

 riously modified eyelids which are grown together with the exception 

 of a mere pin-hole in the center. Apparently the tongue aims at the 

 exact point of focus of the two eyes. Several signs of racial senes- 

 cence are displayed by chameleons: their high compressed bodies, 

 their lack of scales, and the specialized eyes, feet and tails. 



An excellent account of the activities of the chameleon is given by 

 Gadow, accompanied by a composite illustration (Fig. 140). 



" It is most interesting to watch them stalking their prey. Sup- 

 pose we have introduced some butterflies into their roomy cage, 

 which is furnished with living plants and plenty of twigs. The 

 Chameleons, hitherto quite motionless, perhaps basking with 

 flattened out bodies so as to catch as many of the sun's rays as 

 possible, become at once lively. One of them makes for a butter- 

 fly which has settled in the furthest upper corner of the cage. 

 With unusually fast motions the Chameleon stilts along and 

 across the branches and all seems to go well, until he discovers 

 that the end of the branch is still 8 inches from the prey, and he 

 knows perfectly well that 7 inches are the utmost limit to a 

 shot with his tongue. He pauses to think, perhaps with two limbs 

 in the air, but stabihty is secured by a judicious turn of the tail. 

 After he has solved the puzzle, he retraces his steps to the base 



