568 LACERTILIA CHAMAELEONTES CHAP. 



the African continent. One, the common Chameleon, is North 

 African, extending into Andalucia ; two others occur in South 

 Arabia and Socotra, and only one in Southern India and Ceylon. 

 This sub-order is well distinguished from all other Saurian s 

 by several, mostly unique, characters. The tongue is club-shaped 

 and extremely projectile, to a length equal to that of the body. 



The head is usually described as 

 forming a casque, with prominent 

 crests and tubercles. There is no 

 tympanum and no tympanic cavity. 

 The parietal bones, united into one, 

 extend backwards far beyond the 

 occiput, and the tip of this projec- 

 tion is met by a much -elongated 

 supra temporal bone, which, partly 



1 CHAMAELEONTIDAE. f r , .*. , , , 5 



FIG. U8.-Map showing the distri- fused Wlth the Squamosal, helps to 



button of Chameleons. enclose a huge supratemporal fossa. 



The latter is widely open behind. The postfronto-squamosal 

 arch and the postorbital arch are strong. The jugal is widely 

 separated from the quadrate ; the latter stands vertically and is 

 not reached by the pterygoid. There is no columella cranii. 

 The pre- and post-frontals often join to form a supra -orbital 

 roof. The nasals are very small and are excluded from the nares, 

 which are bordered entirely by the enlarged prefrontals and by 

 the maxillaries. The premaxillaries are small and carry no 

 teeth. The latter are acrodont, compressed and tricuspid, and 

 are restricted to the maxillaries and mandibles. 



The limbs are peculiar. Not only are they relatively long and 

 very slender, but two digits are permanently opposed to the other 

 three. On the hand the first three fingers form an inner bundle 

 opposed to the outer, or fourth and fifth fingers. On the foot the 

 inner bundle is formed by the first and second, the outer by the 

 other toes. The shoulder-girdle is of the ordinary Saurian type, 

 but there are no clavicles and no interclavicle. The costal sternum 

 is well developed ; the ribs posterior to those which meet the 

 sternum are very thin and elongated: they meet and fuse with their 

 fellows in the medio- ventral line. These hoops are not connected 

 with their neighbours in front or behind. The tail is prehensile 

 by being rolled downwards ; it is not brittle and is incapable of 

 being renewed. The skin is not covered with scales, but with 



