128 
COMPARATIVE ANATOMY. 
a prong or ploughshare, has made its way to the roots upon 
which it feeds. A conformation so happy was not the gift 
of chance. 
In birds, this organ assumes a new character; new both 
in substance and in form; but in both, wonderfully adapted 
to the wants and uses of a distinct mode of existence. We 
have no longer the fleshy lips, the teeth of enamelled bone; 
but we have, in the place of these two parts, and to perform 
the office of both, a hard substance (of the same nature 
with that which composes the nails, claws, and hoofs of 
quadrupeds) cut out into proper shapes, and mechanically 
suited to the actions which are wanted. The sharp edge 
and tempered point of the sparrow’s bill picks almost every 
kind of seed from its concealment in the plant; and not 
only so, but hulls the grain, breaks and shatters the coats 
of the seed, in order to get at the kernel. The hooked beak 
of the hawk tribe separates the flesh from the bones of the 
animals which it feeds upon, almost with the cleanness and 
precision of a dissector’s knife. The butcher-bird trans¬ 
fixes its prey upon the spike of a thorn, whilst it picks its 
bones. In some birds of this class, we have the cross bill, 
e. both the upper and lower bill hooked, and their tips 
crossing. The spoon bill, enables the goose to graze, to 
collect its food from the bottom of pools, or to seek it 
amidst the soft or liquid substances with which it is mixed. 
The long tapering bill of the snipe and woodcock, pene¬ 
trates still deeper into moist earth, which is the bed in which 
the food of that species is lodged. This is exactly the in¬ 
strument which the animal wanted. It did not want 
strength in its bill, which was inconsistent with the slender 
form of the animal’s neck, as well as unnecessary for the 
Kind of aliment upon which it subsists; but it wanted 
length to reach its object. 
But the species of bill which belongs to birds that live 
by suction, deserves to be described in its relation to that 
office. They are what naturalists call serrated or dentated 
bills; the inside of them, towards the edge, being thickly 
set with parallel or concentric rows of short, strong, sharp- 
pointed prickles. These, though they should be called 
teeth, are not for the purpose of mastication, like the teeth 
of quadrupeds: nor yet, as in fish, for the seizing and retain¬ 
ing of their prey; but for a quite different use. They 
form a filter The duck by means of them discusses the 
mud; examining with great accuracy the puddle, the brake, 
every mixture which is likely to contain her food. The 
operation is thus carried on:—The liquid or semi-liquid sub- 
