226 



CHARACTERS OF VERTEBRATE ANIMALS 



The most extraordinary member of the family, however, is 

 the Stump-tailed Lizard {Trachysaurus rugosus) (fig. 142) of 

 Australia, with short flattened tail, strong limbs provided with 

 well - developed claws, and very prominent regularly - arranged 

 scales. 



10. Chameleons are small tree-inhabiting reptiles, familiarly 

 known as possessing the power of changing the colour of their 

 skins to harmonize with the surroundings for the time being. 



Fig. 142. — Stump-tailed Lizard [Trachysaurus rugosus) 



They exhibit many remarkable peculiarities of structure related 

 to climbing and the capture of their prey, which consists of 

 insects. They form a well-marked group, differing so much 

 from the other subdivisions of lizards that it would probably be 

 better to consider them as a distinct order. The scales are very 

 small and granular, and the remarkable head is possessed of 

 enormous eyes which can be moved independently of one another, 

 while each is provided with a circular eyelid, in the middle of 

 which is a small round hole. There is no external trace of 

 organs of hearing. Both limbs and tail are modified for climbing. 

 The tongue is club-ended and worm-like, and can be rapidly 

 protuded to a distance equalling the length of the body (exclusive 

 of the tail). Being rendered sticky by a special secretion, it 

 forms a very efficient insect-catching apparatus. The lungs of 

 Chameleons are of interesting structure, there being an approach 

 to the air-sacs of Birds (see p. 148), for each lung, though fairly 

 spongy and thick -walled in front, is produced behind into a 

 number of thin-walled slender processes which extend between 

 the various internal organs. It does not appear, however, that 



