THE SPINAL COLUMN OF REPTILES. 165 



course; and, therefore, unless it dart utiawares 

 on its prey, may be avoided without much 

 difficulty. Far otherwise, however, is it in 

 its congenial element; there its powers are all 

 displayed to advantage, and woe to the animal 

 swimming in the river, on which it darts with 

 fierce impetuosity. 



K we turn to the skeleton of the chameleon, 

 with its cUnging linabs and prehensile tail, 

 we find another modification of structiu-e, 

 equally harmonious. In the short neck of 

 this reptile, the vertebrae are reduced to five 

 in number; and the spinous processes of the 

 dorsal vertebrae are very large and broad, 

 forming in the living animal an acute, ele- 

 vated ridge down the middle of the back ; 

 while the ribs inclose a voluminous chest for 

 the ample lungs, which in this animal are 

 singularly developed. 



"We may well contrast the skeleton of the 

 chameleon with that of the frog, one of the 

 amphibia, which is remarkable for its sim- 

 plicity, and the total absence of true ribs. 

 While in a tadpole state, the skeleton of 

 this Avell-known little creature is thoroughly 

 fish-like, the vertebra) having cup-like cavities 

 filled with elastic gelatine, which, being inter- 



