EEPTILES. 



289 



nislies the action of the heart and lungs, slackens the 

 play of all the vital organs, and produces a state of hyberna- 

 tion. A diminution of the temperature to about 40 to 50 

 is almost always fatal to these animals. It is important to 

 bear this physiological law of their economy in recollection 

 when reasoning on the past conditions of the earth in those 

 latitudes where reptile remains are discovered entombed. 



The skeletons of reptiles are found nearly entire in the 

 liasic beds of the oolitic period and in other secondary 

 rocks. "We refer the student who is anxious to become 

 acquainted with the marvellous structure of these denizens 

 of the ancient earth to the magnificent specimens con- 

 tained in the British Museum, and in those of Bristol and 

 Cambridge. 



The lacustrine eocene strata of Hampshire and the Isle or 

 "Wight have yielded nearly perfect carapaces of turtles and 

 the skulls of crocodiles and an alligator. The eggs of 

 chelone are found in the falunian stage of the Gironde, and 

 the coprolites of this class are strewed through many rocks 

 of the oolitic and cretaceous periods, and the foot-prints of 



FIG 196. The Green Turtle (Chelonia midas). 



