110 COMPARISONS OF STRUCTURE IN ANDIALS, 



and naked muzzle, tlie tongue appears to be 

 the great organ of touch as well as prehension ; 

 cattle lick each other's coats with the rough 

 surface of the tongue; but horses nibble or 

 scratch each other's hides with the lips and 

 front teeth. The cow has no fore teeth in the 

 upper-jaw, and the tongue has much more 

 freedom than that of the horse. 



When we turn to the aquatic mammalia, 

 whales, cachalots, and porpoises, with two 

 paddles for limbs, and universally coverfid with 

 a smooth oleaginous skin, spread over an under 

 layer of blubber, we are at a loss to discover 

 any organ in which the sense of touch more 

 especially resides. This sense indeed they can 

 scarcely be supposed to require, the diffused sense 

 of simple feehng over the whole of the external 

 surface is sufficient for their need ; they dart 

 through the waters after their prey, and seize 

 it with a snap of the jaws, and swallow it 

 instantaneously. Perhaps the tongue pos- 

 sesses some sense of touch, and this more 

 especially in the Greenland whale, which feeds 

 on myriads of small marine creatures, as the 

 olio borealis and shrimps, which it takes in with 

 a large volume of water, straining the latter off 

 through the fringed edges of' the plates of 



