CHELONIAN REPTILES. 411 



gressive motion than any of the other orders of 

 reptiles, yet the greater shortness and oblique posi- 

 tion of their limbs, compared with those of mam- 

 miferous quadrupeds, oblige them in general 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 Chameleon walks with great slowness, 

 and apparent difficulty ; and we have seen that, 

 in consequence of the structure of the bones of its 

 neck, the Crocodile, though capable of swift motion 

 in a straight line, is unable to turn itself round 

 quickly. The general type of these reptiles, having 

 reference to an amphibious life, has not attained 

 that exclusive adaptation to a terrestrial existence, 

 which we find in the higher orders of the Mammalia. 

 But before proceeding to consider these, we have 

 to notice a singular group of animals, whose con- 

 formation appears to be exceedingly anomalous, 

 and as if it interrupted the regularity of the as- 

 cending series, of which it seems to be a collateral 

 ramification. 



1^ 5. Chelonia. 



The order of Chelonicm Reptiles, which comprises 

 all the tribes of Tortoises and Turtles, appears to 

 constitute an exception to the general laws of con- 

 formation which prevail among Vertebrated Ani- 

 mals : for instead of presenting a skeleton wholly 



