ANTERIOR LIMBS OF BIRDS, ETC. 77 



enable the animals to ascend smootli walls, 

 and even fix themselves upon the ceilings of 

 apartments. Nor are these lizards the only 

 examples of this peculiar structure of the feet 

 among the reptile tribes : there is a group of 

 frogs, abundant in the warmer latitudes, which 

 are arboreal in their habits, and remarkable for 

 the beauty of their colouring. These frogs 

 are extremely active and restless, and leap 

 from leaf to leaf with admirable address. 

 Often they lurk on the under side of leaves, 

 and dart from their ambush at insects flitting 

 by : they can clear distances of several feet, 

 and attain with the utmost precision the leaf 

 aimed at ; there they settle, and sooner or 

 later dart off to another. In these tree frogs, 

 (and indeed on all the amphibious reptiles,) 

 the toes are unarmed with claws, but each toe 

 is enlarged at the tip, and is there furnished 

 on its under surface with a cushion or sucker, 

 lubricated with a glutinous fluid, and this 

 sucker applies itself so closely to the surface 

 it comes in contact with, as to retain the 

 animal in its position, firmly attached. Never- 

 theless, these suckers are under the will of 

 the animal, and can be disengaged or fixed 

 at pleasure. It is from this power over its 



