42 LIFE ON THE EARTH. 



piece of mechanism by which its long tongue is sud- 

 denly projected, and suddenly retracted, a mechanism 

 of elastic bone, the hyoid or tongue-bone greatly 

 lengthened backward, the horns turned upward in a 

 groove of the cranium and planted in the right nos- 

 tril. Inexplicable on any view but that of a wise 

 co-ordination of the different parts of the structure 

 to answer an appointed end. With this view in our 

 minds we no longer wonder at the long spirally 

 wrapped muscles which govern this elastic bone, or 

 at the terminal armature of the tongue. 



Nor under such an aspect are we confounded by 

 the sudden outrush of the Chamseleon's tongue, 

 which seizes instantly, by its moistened extremity, 

 the fly so patiently watched ; the result of a com- 

 bined mechanism whereby the soft mass is straight- 

 ened, directed, and shot forth like an arrow flying to 

 its mark, and then retracted and folded within the 

 jaws which otherwise could not have received it 1 . 



Life on land presents no less variety of appro- 

 priate adjustments, by which the general types of 

 the Vertebrata and Articulata are made to answer a 

 great diversity of requirements. TO take examples 

 from Mammalia. For pure motion what can be con- 

 ceived more complete than the whole frame, and 



1 These peculiarities of the Woodpecker and Chamseleon and 

 other animals were some of my pleasant studies of Natural His- 

 tory 30 years since. 



