H4 



WATER REPTILES OF THE PAST AND PRESENT 



Flat-headed lizards. — Among the living lizards there is one group, 

 called the monitors, which have so many characters peculiar to 

 themselves that they seem rightfully entitled to an isolated place 

 among the lizards of the present time. The group includes about 

 thirty species, all belonging in the one genus Varanus, and all 

 living in India, Africa, and Australia. In size, some of the species 

 of Varanus are the largest of all terrestrial lizards known in the 

 past or present; in other ways also they have reached the maxi- 

 mum of specialization among lizards. The head is pointed, 

 broad, and flat, and the body and tail are long. They have nine 



Fig. 67. — Varanus, Australian monitor lizard. (By permission of the New York 

 Zoological Society.) 



vertebrae in the neck, a larger number than is to be found in any 

 other terrestrial lizard. Unlike other lizards they have a pro- 

 trusible tongue like that of the snakes. All are carnivorous in 

 habit, feeding upon small backboned animals, insects, and especially 

 upon eggs, which they crush between their teeth while holding 

 them aloft. Most species live wholly upon the land, and some 

 are arboreal. Others, especially those of the Nile, live about 

 water and are excellent swimmers. The terrestrial species have a 

 round tail and small external nostrils, but the water species have 

 the tail much flattened, and the nostrils have large cavities, 

 which, when closed under water, are said to serve as reservoirs of 



