﻿294 ON THE CLASSIFICATION OF BIRDS. 



the meadows long after the sun has set ; and Dr. 

 Richardson mentions that, although it often sits for a 

 long time on the boughs of a tree, it is frequently seen 

 skimming over swampy pieces of ground, and hunting 

 for its prey by the subdued daylight, which illumines 

 even the midnight hours in the high parallels of lati- 

 tude. These two forms we consider as typical of the 

 buzzards ; and so perfectly does the first, which belongs 

 to the subgenus Circus, represent the Fissirostres, that 

 Dr. Richardson's account of its manners is precisely 

 applicable, as every one must perceive, to the common 

 swallow. Fissirostral types either hunt for their prey 

 upon the wing, like the swallow family, or watch for it 

 from a fixed station, like the tyrant fly-catchers and 

 the ordinary buzzards ; while, to show that these op- 

 posite modes of feeding are quite consistent with the 

 same primary type, we find them actually united in the 

 Buteo lagopuSy which thus intervenes between Circus 

 and the common buzzard, and represents at once both 

 the typical and the aberrant Fissirostres : for all these, 

 in fact, capture or seize their prey upon the wing. 



(241.) The relations of the two next groups, the 

 kites and the Tenuirostres, from our comparative igno- 

 rance of the habits of both groups, cannot be traced in 

 their economy ; but this need not be much regretted, 

 since they possess, in common, certain peculiarities of 

 structure which are not to be found in any other birds 

 of their respective circles. The humming-birds have 

 wings fully as long as the swallows, joined to a peculiar 

 elongation of the upper mandible, which they, or any 

 other perching family of slender-billed birds, do not 

 possess. Their feet, moreover, are the shortest of all 

 the Insessores ; so short, indeed, that the tarsus is fre- 

 quently shorter than the hinder toe, while the middle 

 toe scarcely exceeds the lateral ones. Now, upon look- 

 ing to the true kites, comprehending the subgenera 

 Cymindis, Nauclerus, and probably Elcuius*, we ob- 



* We have not an example of this genus before us, but the published 

 figures give an idea that the tarsi are remarkably short 



