192 



ANIMAL FORMS 



Both pairs of limbs are absent, but by wriggling movements 

 of the body this lizard is able to force its way through light 

 soil with considerable rapidity. It is a matter of some 

 difficulty to secure entire specimens, for with other than 

 the gentlest handling the tail severs its connection with 

 the body, as the vertebra in this portion are extremely 

 brittle. This peculiarity, together with its shape, has given 

 it the popular name of glass-snake. Many species of liz- 

 ards will thus detach the tail, a habit which is a means of 

 protection, enabling the animal to scamper away into a 

 place of safety while its enemy is concerning itself with 

 the detached member. Later on a new tail develops, 

 though usually of a less symmetrical form. 



181. Horned toads. The horned toads (Phrynosoma) are 

 lizards peculiar to the hot, sandy deserts and plains of 





FIG. 115. Gila monster (Heloderma susjxctum). One-third natural size. 



Mexico and the western United States. The body is com- 

 paratively broad and flat, almost toad-like, and is covered 

 with scales and spines of brownish and dusky tint, so like 

 dried sticks and cactus spines in form and color as to ren- 

 der them difficult of detection. In captivity they readily 



