ON LIZARDS IN GENERAL. 149 



feet ; having an active^ lengthened body, terminating in 

 a tail_, and covered with small scales, but not with 

 shields or plates, as in the crocodiles and tortoises : such 

 reptiles are known in common language as lizards and 

 chameleons : and they constitute the second, or sub- 

 typical order of the class of reptiles. 



(150.) The general characters most prevalent in this 

 assemblage of animals may be thus briefly stated. In 

 their external form they may be compared to thick-bodied 

 serpents, furnished with feet : the mouth is always 

 armed with teeth, and the skin is protected by siAall 

 scales, more or less crowded : they are all provided 

 with a tail, which is generally very long, thick at the 

 base, and pointed at the end. In such as pass into the 

 serpents, the feet are very small, and are sometimes con- 

 fined to one pair. They are well distinguished, also, 

 by many anatomical peculiarities : the heart is com- 

 posed, like that of tortoises (Cheloxides), of two auri- 

 cles, and of a ventricle, sometimes divided by imperfect 

 partitions : the ribs are moveable, attached to the 

 sternum, and capable of being raised or depressed for 

 respiration. Their generation is almost universally 

 oviparous : the eggs are more or less hard, and the 

 young are born with the form of their parents. The 

 whole of these reptiles are carnivorous, living upon 

 other animals of inferior size and strength to them- 

 selves, in a living state, such as small birds, worms, and 

 insects : their digestion is very slow : they eat but sel- 

 dom, and never drink. In their motions, the majority 

 are possessed of peculiar agility upon land, for none of 

 them, like the crocodiles, inhabit the water. They 

 ascend perpendicular walls and trees with nearly as 

 much swiftness as if they were running upon a level 

 surface ; others, as the chameleons, although not active, 

 have their feet adapted solely for grasping and climbing ; 

 while the geckos, or nocturnal lizards, as we have often 

 witnessed in Sicily, run over the ceiling with their 

 backs downwards, as quickly as if they were upon the 

 ground. 



