PTERODACTYLUS. 



Fig. 15 



as the body, and probably sustained a fold of skin, fitted to 

 perform the functions of wings.* To indicate this singular con- 

 formation, the generic name of PTERODACTYLUS has been given 

 to these fossil Saurians. 



ORDER OF OPHIDIANS, OR SERPENTS. 



39. We ordinarily group with Serpents, or Ophidians, all rep- 

 tiles that have a cylindrical, elongated body, without extremities ; 

 but in order that the classification of these animals may represent 

 the modifications introduced by nature in their organization, and 

 indicate the degree of physiological importance of these diffe- 

 rences, it becomes necessary to separate from the serpents, some 

 apodous reptiles in which respiration is at first branchial, then 

 pulmonary, as it is in ordinary Batrachians. On the other hand, 

 the passage between the Saurians and Ophidians is so gradual, 

 that the limits between these two orders are somewhat arbitrary. 

 Some naturalists even think, they should not be separated, and, 

 according to others, it would be proper to range in the division 

 of Saurians, those reptiles that, by their internal organization, 

 are removed from the common type of Ophidians, and approach 

 that of the Scincoidea. 



40. The apodous reptiles, which are in a manner intermediate 

 between the Saurians and the Serpents properly so called, are 



* The dotted line indicates what it is presumed, was the outline of the animal. 



39, What description of reptiles belong to the order of Ophidians. 



40. What are the general characters of the Angues? What are their 

 habits? Upon what do they feed ? What aru Glass-Snakes ? What are 

 the characters of the common Angue of Europe ? 



