﻿164 ON THE CLASSIFICATION OF BIRDS. 



fact is established by experience, and by comparative 

 anatomy : we know that the crowing of a cock may be 

 heard at a far greater distance than the shout of a man, 

 even had he the lungs of Stentor, and it may be even 

 questioned whether the same remark may not be appli- 

 cable to the full and sonorious warbling of the thrush. 

 We have no data to estimate the comparative loudness 

 of voice between quadrupeds and birds, in proportion to 

 their sizes : nor is it very material to labour upon such 

 nice distinctions. It is only in these two typical classes 

 of the vertebrated circle, if we except the hissing of ser- 

 pents, and the croaking of frogs, that the voice is suf- 

 ficiently developed to emit sounds, audible and definite. 

 The voice of many quadrupeds is capable of different 

 degrees of intonation which, as they are understood by 

 their kind, is without doubt a language. The lowing 

 of the cow, when slowly wending tf o'er the lea," to the 

 farm yard, is very different from that which it utters 

 when separated from its young ; and, again, from the 

 bellowings of fear or of rage. In the dog, how many 

 varied intonations will be found : but it is among 

 birds alone that these sounds assume harmonious grada- 

 tions. But has nature restricted the power of uttering 4 

 sounds to the vertebrated circle ? Every entomologist 

 knows the contrary. A large portion of the natural order 

 of Hemiptera Lin., among insects, are, perhaps, the most 

 noisy beings in creation ; nor is this noise altogether 

 unmusical : the ancients, indeed, so much admired the 

 shrill chirpings of the Cicada, that one of their poets 

 has made this insect the subject of an ode. Now the 

 order Hemiptera, in the circle of the class Ptihla, or 

 winged insects, occupies precisely the same station as the 

 class of birds fills in the circle of the vertebrata. So 

 that nature, ever true to her beautiful system of repre- 

 sentation, makes the Hemiptera, by this peculiar faculty, 

 to be the birds of the insect world : both perch upon trees 

 and both sing (though by different means), for a long 

 continuance, and in their most alluring notes, during the 

 season of courtship. Detach the Cicadas from the 



