REPTILES. 285 



SECTION III. 



THE CLASS OF REPTILES. 



THE Class of Reptiles comprises cool-blooded, ovipa- 

 rous vertebrates, which are covered with scales, and which 

 lay their eggs upon the land, and whose young closely 

 resemble the parents from the time they leave the shell. 

 They breathe by lungs, have a heart with two auricles 

 and one ventricle, and their digestion is slow. The rep- 

 tilian heart, at each of its contractions, transmits to the 

 lungs only a portion of the blood which comes to it from 

 the various parts of the system, and the remainder goes 

 into the circulation again without having been subjected 

 to respiration. Thus the blood of these animals is acted 

 upon by oxygen far less than in Mammals and Birds, 

 and their temperature is correspondingly lower, and their 

 habits more sluggish. The smallness of the pulmonary 

 vessels enables Reptiles to suspend the process of respi- 

 ration without arresting the progress of the blood ; and 

 hence they are able to remain much longer beneath the 

 surface of the water than any of the animals described 

 in the previous pages. The cells of the lungs are less 

 numerous, and larger, than in the higher animals. The 

 brain of Reptiles is comparatively small, and their sensa- 

 tions blunt. They continue to live and exhibit voluntary 

 motions long after losing the brain, and even after the 



in existence. It is allied to the Columbse. The Solitaire is another large 

 extinct bird of the same region. 



The Moa, or Dinornis, a bird whose remains are found in New Zealand, 

 was twelve or fourteen feet high, and the tibial bone thirty-two inches long ; 

 and its egg, which has been found fossil, fills a man's hat ! 



The ALpyornis of Madagascar was, as its bones show, twelve feet high, 

 and its fossil egg is thirteen and a half inches long ! This and the Moa, 

 and some other extinct birds whose remains are found in the same regions, 

 are allied to the Struthionidae. 



