(f 



HINTS FOB STUDYING OBNITHOLOQT. S6l 



varied. You may perhaps be at a loss to comprehend 

 how a swallow, a humming-bird, and a crow, can belong 

 to the same order. But look to the characters of the 

 order. All birds having their hind toe or toes placed 

 upon a level with the ground, are perchers, provided, of 

 course, that the claws are not retractile ; for this latter 

 circumstance distinguishes the birds of prey. You have, 

 therefore, only to see if the foot of a swallow, humming- 

 bird, and crow, are so formed: this is y owe first point 

 to ascertain. Other distinctions follow in their proper 

 order. Having, therefore, ascertained this primary cha- 

 racter, you next look to the bill, the foot, and the claws. 

 If the bird before you has the upper mandible distinctly 

 notched, the legs of moderate length, and the toes three 

 before and one behind, you may conclude at once that 

 it belongs to the tribe of Dentirostres. If, oh the con- 

 trary, you see that the bill is very slightly, if at all, 

 notched near the end, but that the feet are still mode- 

 rately long, as in the crow or sparrow, you have the 

 general characters of the Conirostres. All other birds 

 (and they amount to many hundreds) which do not pos- 

 sess these characters, whatever their general appearance 

 may be, you may safely throw out of these two prin- 

 cipal and typical tribes. You will find that their legs 

 are much shorter ; that their toes are either united at 

 their base, or placed two and two ; and that their bill 

 is without a notch : they, consequently, belong to the 

 large aberrant circle of the Curtipedes, or short.footed 

 birds. 



(44-6.) Here, however, you will begin to see that 

 nature's groups cannot be rigorously defined: and 

 this fact will become more and more apparent, in pro- 

 portion as you proceed into details. It is one of the 

 chief, or typical, distinctions of the Dentirostres to have 

 the bill distinctly notched ; but this character disappears 

 in some of the titmice (Farus), and is not perceptible 

 in all the mock-birds (Orpheus). The long-legged 

 thrushes (Crateropodince) have the bill entire. All these 

 groups, nevertheless, have the feet so long, and so per-^ 



