186 ANIMAL FORMS 



forms and sizes, always of definite arrangement, cover the 

 body. The scales are always colored, in some species as 

 brilliantly as the feathers of birds, and usually harmonize 

 with the surroundings of the animal, enabling it to escape 

 the attacks of its many enemies. Altogether the lizards 

 are a very attractive group of animals. As in the salaman- 

 ders, the vertebral column is usually of considerable length, 

 but it too presents a lighter appearance and a greater flexi- 

 bility. Slender ribs are present, and a breast-bone and the 

 girdles which support the limbs. Although more ossified 

 than in the amphibians, the skull still continues to be com- 

 posed here and there of cartilage. The roof also is yet 

 incomplete, but with the firm plates on the surface of the 

 head ample protection is afforded the small brain under- 

 neath. As above mentioned, the limbs are slender and 

 insufficient to support the body, which accordingly rests 

 upon the ground, and by its wrigglings and the pushing of 

 the limbs is borne from place to place. It will be recalled 

 that some of the salamanders living in subterranean haunts 

 and burrowing in the soil have no need of limbs, and the 

 latter have accordingly disappeared. This condition is 

 paralleled by certain species of lizards. The blindworms 

 (which are neither blind nor worms, but true lizards, though 

 snake-like in appearance) are devoid of limbs, as are also 

 the " glass-snakes." In some species the hinder pair arise 

 in early life, but they remain small, and ultimately disap- 

 pear. In almost all lizards the tail is very brittle, breaking 

 at a slight touch. In such case the lost member will grow 

 again after a time. 



177. The snakes (Serpentes). The snakes are character- 

 ized by a cylindrical, generally greatly elongated body, in 

 which the divisions into head, neck, trunk, and tail are not 

 sharply defined. As we have seen, this is also true of cer- 

 tain lizards, but the naturalist finds no difficulty in detecting 

 the differences between them. Another peculiarity of the 

 snakes is in the great freedom of movement of the bones 



