TASTE. 103 



liquid," he says, " or semi-liquid substances, in which 

 the animal has plunged her bill, she draws, by the 

 action of her lungs, through the narrow interstices 

 which lie between these teeth ; catching, as the 

 stream passes across her beak, whatever it may happen 

 to bring along with it that proves agreeable to her 

 choice, and easily dismissing all the rest. Now, 

 suppose the purpose to have been, out of a mass of 

 confused and heterogeneous substances, to separate for 

 the use of the animal, or rather to enable the animal 

 to separate for its own, those few particles which 

 suited its taste and digestion ; what more artificial, or 

 more commodious, instrument of selection could have 

 been given to it than this natural filter ? It has been 

 observed also (what must enable the bird to choose 

 and distinguish with greater acuteness, as well pro- 

 bably as what greatly increases its luxury) that the 

 bills of this species are furnished with large nerves,- 

 that they are covered with a skin, and that the 

 nerves run down to the very extremity*.'' 



M. Geoffrey St. Hilaire, pursuing his Theory of 

 Analogues, of which we have already given a cha- 

 racteristic specimen, proceeds to compare the filtering 

 apparatus in the mouths of the whale and the shoveller 

 (Rhynchaspis clypeata, LEACH) with the palates of 

 other animals which he finds to be lined with similar 

 wrinkles, the difference of one species from another 

 consisting in little more than the greater or less degree 

 of thickness in the cartilaginous plate^ forming the 

 tranchant wrinkles. In the macaw this forms a single 

 mass, only marked with a few streaks f. 



The various forms, indeed, which we meet among 

 the bills of birds, are wonderfully adapted to their 

 wants. Instead, as Paley remarks, of the fleshy lips 

 and teeth of enamelled bone, there is "to perform the 



* Nat. Theology, p, 225. f Systeme Dentaire, p. 15. 



