DIVISION OF SAURIANS. 41 



mechanism as in mammals and birds, that is, by the alternate 

 dilatation and contraction of the cavity of the thorax, effected by 

 the action of the ribs. 



8. The order of Saurians may be divided into six families, 

 namely : Crocodilians^ Lacertiuns, Chumcleonians^ lguanians % 

 d'rckotians, and Scincoidians, which may be distinguished by 

 the following characters: 



SAURIANS, 



f . 



jrjl 



en 



l\ 



ro _ 



ir 



r* 



Certain fossil reptiles, which cannot be classed in any one of 

 the above families, are also referred to this order : some of them 

 were formed for swimming exclusively, and others for flight. 



8. What is the division of the order of Sauria / 

 3* 



