296 REPTILES. 



single series of wide parallel horny shields, placed transversely ; beneath the tail, these 

 are disposed in a double series (Fig. 322). 



FIG. 321. HEAD OF RINGED S.VAKE. FIG. 322. BELLY AND TAIL SHIELDS. 



FAMILY V. DOUBLE WALKERS. 



The Fifth Family of Serpents (Amphisbceitidce) contains 

 The Double Walkers (Amphisb/zna),* so called because it is difficult 

 to make either head or tail of them, seeing that they progress equally well with 

 either end foremost. They have much resemblance to the slow-worms deli- 

 neated in the next figure, feed chiefly upon ants and other insects, and are 

 perfectly harmless. The species are few, and abound in the tropical parts of 

 both hemispheres. 



ORDER SAURiA.f 



The Saurian Reptiles, or Lizards, might almost be described as 

 serpents supported upon legs ; indeed, in some of the genera the 

 resemblance to serpents is so great that they might easily be mis- 

 taken for those animals. In general, however, the legs are suffi- 

 ciently developed to be used as the principal instruments of loco- 

 motion ; they are then four in number, and the toes are armed 

 with claws. The skin of lizards is covered either with scales or 

 with granulations ; but in other respects they are most variously 

 constructed, as will be seen by inspecting the tabular view of 

 their classification in the following page. (See p. 297.) 



The habits of these various families are very diverse. Some, 

 as the crocodiles, inhabit lakes and rivers. Others, as the iguanas, 

 live among the foliage of trees. Some, as the dragons, perform 

 a sort of flight like that of the flying squirrels. The lizards delight 

 to bask in the genial rays of the sun on exposed sandy banks ; 

 others conceal themselves in humid forests, beneath stones and 

 rotten logs. Some crawl with slow and languid efforts, others run 

 with a celerity that the eye can scarcely follow. Though found 

 in almost all countries, the fervent sun of the tropics seems most 

 favourable to their existence, and it is more especially in such 

 regions as have a moist as well as a hot atmosphere that they 

 abound. 



* d.u0i's, amphis, both ways ; /Sdu/w, baino, to go. f cravpos, sauros,. a lizard. 



