CLASS III. IIEPTILIA: ORDER 1. CITELOXIA. 



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The Reptilia comprise four orders very distinct in some respects, thougli united in otliers : the 

 Chelonia, or Tortoises ; the Loricata, or Crocodiles ; the Sauria, or Lizards ; and the Ophidia, 

 or Serpents. These are generally regarded with little favor by mankind, but their natural history 

 is nevertheless full of interest. With the exception of a few tortoises they are all carnivorous 

 animals. They have all a slow circulation; their blood is cold, that is, but little above the tem- 

 perature of the surrounding medium ; the amount of their aggregate muscular energy is less than in 

 the mammalia ; their movements are generally crawling and swinnning ; and though some of them 

 leap and run with celerity on certain occasions, their habits are generally sluggish, their digestion 

 slow, their sensations obtuse, and in cold or temperate climates they pass nearly the whole 

 winter in a state of lethargy; they continue to live and to execute voluntary movements for a 

 considerable time after having been deprived of the brain, and even when the head is severed 

 from the body. Their heart pulsates, in some cases, for many hours after it has been detached, 

 and its loss does not deprive the body of mobility for a still longer period. Their blood not being 

 warm, they do not require teguments capable of retaining heat ; they are accordingly covered 

 with shells, scales, or naked skin. No reptile incubates its eggs. In certain genera of batrachians 



