462 THE MECHANK AL FUNCTIONS. 



of the Remora*' By its means the animal is 

 enabled to walk securely upon the smoothest 

 surfaces, even in opposition to the tendency of 

 gravity. It can run very quickly along the 

 walls or ceiling of a building, in situations where 

 it cannot be supported by the feet, but must 

 depend altogether upon the suspension derived 

 from a succession of rapid and momentary ad- 

 hesions. 



Although the Sauria are better formed for 

 progressive motion than any of the other orders 

 of reptiles, yet the greater shortness and oblique 

 position of their limbs, compared with those of 

 mammiferous quadrupeds, obliges them in ge- 

 neral to rest the weight of the trunk of the body 

 on the ground, when they are not actually 

 moving. None of these reptiles have any other 

 kind of pace than that of walking, or jumping ; 

 being incapable of performing either a trot or a 

 gallop, in consequence of the obliquity of the 

 plane in which their limbs move. The Chame- 

 lion walks with great slowness and apparent 

 difficulty ; and we have seen that, in conse- 

 quence of the structure of the bones of its 

 neck, the Crocodile, though capable of swift mo- 

 tion in a straight line, is unable to turn itself 

 round quickly. The general type of these rep- 

 tiles, having reference to an amphibious life, has 



* Philosophical Transactions for 18 16, p. 151, and 323. 



