LIZARDS 231 



are covered in lizards and snakes with a parchment-like skin, in 

 chelonians and crocodiles with a hard calcareous shell, and deposited 

 in protected spots or in the earth. (Give examples.) They are hatched 

 by the warmth of the air or soil. Some species, in which the eggs are 

 retained so long in the body of the female that the young emerge from 

 them before they are laid, are termed viviparous. 



ORDER I. : LIZARDS (SAURIA). 



Body elongated, sometimes vermiform, covered with scales or scutes ; two 

 pairs or one pair of limbs, or limbs entirely absent. A shoulder girdle 

 always present. The bones of the face are not movable. Teeth not 

 lodged in sockets. Eyes usually provided with lids. 



The Sand Lizard (Lacerta agilis). 

 (Length about 8 inches.) 



A. Habitat. 



This harmless animal lives on hills covered with low shrubs, on stone- 

 heaps, heaths, the edges of woods, dry ditcheB, and railway embank- 

 ments—in fact, in all places well exposed to the sun's rays, warmth being 

 one of the necessary conditions of its life* The lizard feels at its best 

 when the summer sun sends its hottest rays down upon the earth and 

 man seeks eagerly the cool shade (see p. 230). Eain and cold weather, 

 on the other hand, it dislikes, and at such times creeps for shelter into 

 holes in the earth. This dependence of the lizard on warmth explains — 



B. Its Distribution. 



Its range does not extend beyond Southern Sweden and the South of 

 England. In Central Europe, on the other hand, it is to be met with in 

 all suitable localities. 



C. Colour. 



The colour of its skin is very jariable, and in a marked degree 

 adapted to that of the ground whiclfit frequents. Hence the ease and 

 rapidity with which the animal escapes from sight when pursued in the 

 grass. The skin of the female is always of an earthy colour (grey or 

 brown, with several rows of white, brown-edged spots). In the male, on 

 the other hand, a more or less vivid green tint usually predominates, 

 which, however, is in no way conspicuous amidst the grass. The head 



* In German Eidechse, i.e., lizard, is equivalent to sun-worm. 



