SNAKES 



131 



the head, and the tail are drawn inside, and the box is 

 pulled down tightly by muscles to meet the cover. 



The term turtle is often applied to aquatic forms, and 

 the term tortoise to those living on land. Sea turtles 

 attain a length of six or 



eight feet and weigh 





Figure 129. — Head of a Rattlesnake. 



Dissected to show the poison gland, a, 

 and its relation to the tooth. (Duver- 

 moy.) 



sometimes as much as a 

 thousand pounds. The 

 flesh of the green turtle 

 and of the terrapin 

 (ter'ra-pin) is used for 

 food. 



129. Lizards. — There 

 is a great variety of 

 lizards. A common 

 lizard is the chameleon 



(ka-me'le-un), which has the power of changing the 

 intensity of the color in the skin by moving the color 

 material nearer the outer surface or drawing it away. 

 The horned toad of the Western United States is a lizard 

 with scales of varying length which give it a horny 

 appearance. Horned toads, instead of laying eggs, have 



the eggs hatched while 

 yet in the oviducts and 

 the young horned toads 

 are born alive. A poison- 

 ous lizard is the Gila 

 (he'la) monster that oc- 

 curs in New Mexico and 

 Arizona. It has the poison glands in its lower jaw. 



130. Snakes. — Snakes are legless vertebrates with long, 

 cylindrical bodies covered with scales. They move by 

 means of the scales (scutes) on the under side of the 

 body. Most snakes lay eggs, but a few bring forth living 



Figure 130. — Rattles of Rattlesnake. 



