1 



.350 THE SENSORIAL FUNCTIONS. 



said of Serpents, that their whole body is a hand, 

 conferring some of the advantages of that instru- 

 ment. Helhnan has shown that the slender bifur- 

 cated tongue of these animals is used for the pur- 

 poses of touch. 



In those species of Lizards which are enabled 

 by the structure of their feet to clasp the branches 

 of trees, as the Gecko and the Chameleon, and 

 whose tails also are prehensile, we must, for the 

 same reason, presume that the sense of touch exists 

 in a more considerable degree than in other Saurian 

 Reptiles, which do not possess this advantage. 

 The toes of Birds are also well calculated to per- 

 form the office of organs of touch, from the number 

 of their articulations and their divergent position, 

 and from the papillae with which their skin abounds; 

 accompanied as they are with a large supply of 

 nerves. Those birds, which, like the Parrot, 

 employ the feet as organs of prehension, probably 

 enjoy a greater developement of this sense. The 

 skin which covers the bills of aquatic birds is sup- 

 plied by very large nerves, and consequently pos- 

 sesses great sensibility. This structure enables 

 them to find their food, which is concealed in the 

 mud, by the exercise of the sense of touch residing 

 in that organ. A similar structure, probably 

 serving a similar purpose, is found in the Orni- 

 thorhynclms. 



Among Mammalia, we find the seat of this sense 

 frequently transferred to the lips, and extremity of 

 the nostrils ; and many have the nose prolonged 

 and flexible, apparently with this view. This is 

 the case with the Shrew and the Mole, which are 

 burrowing animals, and still more remarkably with 



