DISTRIBUTION OF ORGANISMS. 



195 



that looseness of structure and adherence which is carried to so 

 remarkable an extent in the serpents, which, being obliged to 

 take their prey entire, could not otherwise swallow it. The 



FIG. 102. 



FIG. 103. 



Bimanus. 



Seps. 



varanians, too, move in a serpentine manner, using their long 

 tail to aid their progression, and to enable them the better to 

 leap upon their prey j peculiarities in which they greatly re- 

 semble the serpents. In the last lacertilia, the ribs are in- 

 creased in number, the two pairs of limbs are removed farther 

 and farther from each other, and become small and weak ; in 

 some species the anterior, and in other the posterior pair, alone 

 remain ; until at last they are reduced to mere rudiments 

 which do not appear above the skin. The common slow-worm 

 is an example of a lacertilian in this state. At the same time, 

 to suit the necessities of a body considerably attenuated, one 

 of the lungs is gradually shrunk up, until at length, in the 

 true serpent, only a vestige of it remains. Such is the actual 

 history of the great serpent families reductions from the 

 lacertilia, to suit a life generally skulking and furtive j and 

 there could not well be a more lively illustration of the doctrine 

 of the transformation of animals. It furnishes a strong proof of 

 the readiness of nature for reduction as well as advance, ac- 

 cording as circumstances shall dictate. Many existing serpents 



