390 THE SENSORIAL FUNCTIONS. 



little vermiform processes called barbels, which 

 in some species are appended to the mouth, 

 may be subservient to this sense.* These pro- 

 cesses in the Silurus glanis are moved by par- 

 ticular muscles. 



Serpents, from the great flexibility of their 

 spine, are capable of grasping and twining round 

 objects of almost any shape, and of taking, as 

 it were, their exact measure. This conformation 

 must be exceedingly favourable to the acquisi- 

 tion of correct perceptions of touch. As it is 

 these perceptions, which, as we shall afterwards 

 find, lay the foundation of the most perfect ac- 

 quaintance with the tangible properties of sur- 

 rounding bodies, we may presume that this 

 power contributes much to the sagacity possessed 

 by these animals. It has been said of Serpents, 

 that their whole body is a hand, conferring some 

 of the advantages of that instrument. Hellman 

 has shown that the slender bifurcated tongue 

 of these animals is used for the purposes of 

 touch, t 



In those species of Lizards which are ena- 

 bled by the structure of their feet to clasp the 

 branches of trees, as the Gecko and the Cha- 



* These kind of tentacula are remarkable for their length and 

 mobility in the LopJiins piscatorius, or Angler ; and it is said 

 that they are employed by the fish, while lurking in ambush, as 

 a decoy to other fishes, which they entice by their resemblance to 

 worms. 



t Quoted by Blumenbach. 



