520 APPENDIX. 



The two lateral fins, which are analogous to the 

 anterior extremities in the quadruped, are com- 

 monly small, varying however in size, and seem 

 to serve as a kind of oars. 



To ascertain the use of the fin on the back is 

 probably not so easy, as the large Whalebone and 

 Spermaceti Whales have it not ; one should other- 

 wise conceive it intended to preserve the animal 

 from turning. 



I believe, like most animals, they are of a 

 lighter colour on their belly than on their back : 

 in some they are entirely white on the belly ; and 

 this white colour begins by a regular determined 

 line, as in the Grampus, Piked Whale, &c. in others 

 the white on the belly is gradually shaded into 

 the dark colour of the back, as in the Porpoise. 

 I have been informed that some of them are pied 

 upwards and downwards, or have the divisions 

 of colour in a contrary direction. 



The element in which they live renders some 

 parts which are of importance in other animals 

 useless to them, gives to some parts a different 

 action, and renders others of less account. 



The tongue is flat, and but little projecting, as 

 they neither have voice, nor require much action 

 of this part in applying the food between the 

 teeth for the purpose of mastication or degluti- 

 tion, being nearly similar to fish in this respect as 

 well as in their progressive motion. 



In some particulars they differ as much from 

 one another as any two genera of quadrupeds I 

 am acquainted with. 



