162 COMPARISONS OF STRUCTURE IN ANDIALS. 



crushes its prey to death by encircling it in 

 its folds; grasping any fixed part or object 

 with its taU, it is by means of this peculiar 

 action of the ribs, the creeping of which 

 beneath the skin may be perceived, that it 

 tightens its compression, till the very bones 

 of the victim give way. Thus it is, also, 

 that, when a powerful snake is held in the 

 grasp, the creeping of the ribs may be dis- 

 tinctly felt ; and with such power do they 

 work, that not without great difficulty can 

 the reptile be prevented fi'om gliding 

 through the hand ; for every step it takes 

 it improves upon, and even the firmness of 

 the grasp, unless so tight as to prevent the 

 muscles from acting, seems rather to assist 

 its eflPorts. 



With respect to the saurian reptiles, we find, 

 as might be expected, various modifications in 

 the spine, and the parts immediately con- 

 nected with it, as we proceed through this 

 multitudinous order of reptiles, from the croco- 

 dile to the blindworm. As a general rule, it 

 may be observed, that the vertebras are 

 numerous, principally oAving to the length of 

 the tail. In most species, the cervical ver- 

 tebrae are seven or eight in number ; but the 



