ORDER SAURIA. l69 



from the central plane of the body, where the weight is par- 

 ticularly exerted. 



When the saurians which are provided with only two 

 limbs, or the mere rudiments of limbs, such as the chalcides, 

 bipeds, &c., repose upon the ground, they form circles with 

 their body above or around each other, and the head is 

 raised above those circumvolutions. 



Certain saurians climb with a wonderful degree of facility. 

 In this point of view the cameleon, among the reptiles, seems 

 to be as well provided as the quadrumana among the mam- 

 malia, in consequence of its hands, claws, and prehensile tail. 



The lizards, anolis, the geckos, and tupinambis in general, 

 Avalk and run with great agility ; others swim by the as- 

 sistance of their limbs and the central part of the tail, while 

 others push forward or backward by an impulsion of the 

 body, or the alternate application of one or more of their 

 lower parts against the ground, in a manner very analogous 

 to that of the serpent tribes. 



The dragons, which belong to this order, are the only 

 reptiles possessing the capacity of flight. For this purpose 

 they are provided, on each side, with a membrane between 

 the feet, which unfolds like a fan, and bends at the will of 

 the animal, by the assistance of osseous radii articulated on 

 the dorsal vertebrse, and which are substituted for the first 

 six false ribs. 



All physiologists are agreed to consider, in animals in 

 general, the actions of walking and running so intimately 

 connected, that it Avould be difficult to establish any certain 

 distinction between them. The saurian quadrupeds do not 

 deviate in this respect from the common rule, and there exists no 

 difference between their walking after a certain mode, and their 

 running; the latter, as in the mammif era, being most commonly 

 performed by the complicated mechanism of the walk and leap. 



