THE TRANSITION TO LAND 



387 



the few animals that are able to exist on the hot, dry, sandy deserts, but 

 they are also found in moist forests and even swimming in the water. 

 Some move so swiftly that they appear as a streak to the eye ; others 

 move so slowly that they seem to be in slow-motion movies. Some have 

 well-developed limbs ; some have none at all and may be mistaken for 

 snakes. 



Many lizards, at one time or another, are accused of being poisonous, 

 but there is only one species in the United States that deserves this accu- 

 sation. This is the Gila monster; it is a clumsy, thick-bodied lizard with 



&v 



, rsi* 



Photo by Winchester 



Fig. 26.9 A Gila monster. This is the only poisonous lizard in the United States. 



Its poison sacs are in the lower jaw and grooved teeth carry the venom into an animal 



that is bitten. Although it looks and acts like a sluggish creature it is capable of rapid 



movements accompanied by snapping jaws that cause it to be respected. 



Histrr 



Fig. 26.10. 



Texas horned lizard. Its appearance in such a close-up view reminds one 

 of the ancient dinosaurs. 



