244 BRANCH CHORDATA 



wriggling body motion. " Two aortic branches, a left and a 

 right, survive in lizards."^ 



Lizards are very various in size, shape, color, and habitat. 

 Most of them are terrestrial, some burrow, some are semi- 

 aquatic, and still others are arboreal. They are generally cov- 

 ered with horny epidermal plates and shed their skin entire. 



The shoulder girdle and sternum are present. The " flying 

 dragons " of the Indo-Malayan countries have "a pair of wing- 



Fig. 200. — Ildodd'inn I I i()i-()iimi>, lizard. (From Holder's "Zoology," 

 American liook Co., I'uhlislicrs ) "The blunt tail of the Gila Monster is 

 actually the reservoir for the storage of nourishing fat." — Ditmars' 

 "Reptiles of the World." 



like membranes supported l)y five or six elongated posterior 

 ribs, which they use as a parachute or fold up like a fan." 



Food. — Most lizards are insectivorous, eating small animals 

 also, but some are herbivorous, living upon buds, V)lossoms, and 

 tender leaves of plants. 



Special Senses. — The eyes are usually provided with an 

 upper and a lower movable eyelid and with a transparent nicti- 

 tating membrane. The tympanic membrane is situated in a 

 slight depression behind the eye. The tongue is free and both 

 jaws are armed with teeth. The mouth is not distensible. 

 1 Packard. 



