CHAPTER XXIX. 

 THE LIZAKDS, SNAKES, AND OTHER REPTILES. 



WE will select as an example of the reptiles our common 

 lizard, which lives in pine woods as far north as Pennsyl- 

 vania. Its scientific name is Sceleporus undulittus. If 

 we compare a lizard with a salamander, we notice that the 

 general shape of the body is the same, but that the lizard 

 differs in the body being covered with scales, and the toes 

 ending in claws. The number of toes on each leg is usually 

 five. The eyes are protected by an upper and lower eye- 

 lid, and there is a nictitating membrane at the inner angle 

 of the eyes, so that, as in birds, lizards, which are crea- 

 tures of the bright sunlight, can withstand the direct rays 

 of the sun. While in the lizard the nostrils are not well 

 marked, they are so in the turtle and alligator. For the 

 first time we meet with true lips. Though the lizard runs 

 swiftly, darting up and down trees, yet it slides along on 

 its belly, pushing itself forward by its legs, not lifting its 

 body above the surface over which it moves. 



When we compare the skeleton of a lizard with a sala- 

 mander's, there are important differences; the vertebrae 

 are usually hollow in front and rounded behind, and the 

 skull is much more like that of a bird than a salamander ; 

 and, as in birds, it is connected with the spinal column by 

 one condyle. The lungs are long and sack-like, but con- 

 nect with the back of the mouth by a long windpipe, as in 

 birds. The brain is also better developed than that of any 

 amphibian, and the heart and circulation are adapted to 

 the more active habits of the lizard. 



The lizard, like birds, lays a few very large eggs, and 



