EEPTILES. 287 



could only have appeared by a special act of creation, as it 

 would be fatal to the hypothesis of development to admit 

 that higher organisms could become the progenitors of lower 

 forms, 



In fine, the history of fossil fishes supplies abundant 

 evidence in support of the opinion that the Almighty has, 

 from time to time, created those forms of life which were 

 best adapted to the changing conditions of the earth's sur- 

 face. Hence we see families and genera appearing in great 

 numbers, destined to live for a limited time, and to become 

 extinct with the close of the stage they characterise. 



CLASS II. EEPTILES. 



The class Eeptilia is one of the most interesting to the 

 palaeontologist, as the fossil remains of many of its extinct 

 forms present, in some, remarkable adaptations of structure 

 to their mode of life, in others dimensions so gigantic, and 

 in all, a geographical distribution so different from the 

 actual condition of nature, that we enter upon the inquiry 

 with an enthusiasm equal to the novelty of the subject. 



The class is divided into four Orders : The CHELONIANS, 

 or Tortoises ; the SATJEIANS, or Lizards ; the OPHIDIANS, or 

 Serpents, and the BATB,ACHIAIS T S, or Frogs and Salamanders. 

 This class comprehends all the vertebrated animals with cold 

 blood, whose respiration in the adult state (if not in early 

 life) is aerial and incomplete. The head is small, and the 

 body is for the most part much elongated. The extremities 

 are sometimes rudimentary or absent, as in serpents, but in 

 general they are four in number, and are adapted for walking, 

 swimming, or flying. All the parts of the skeleton present 

 important modifications in the different orders. 



The skull is always small and the face elongated. The 

 lower jaw is composed of several pieces, and is articulated 

 to the upper jaw by a distinct iDone (the tympanic) ; some- 

 times this bone is a moveable lever for the purpose of increas- 

 ing the gape. The upper jaw is in general immoveable. In 

 some reptiles, as the lizards and the tortoises, the lateral 

 bones of the skull arch over and cover the temporal bones, 

 and thus make their cranium appear much larger than it in 

 reality is. The skull is in general slightly moveable, and 



