A treatise on the geography and classification of animals / By William Swainson.

  • Swainson, William, 1789-1855.
Date:
1835
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the geography and classification of animals / By William Swainson. Source: Wellcome Collection.

    377/390 (page 361)
    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 your 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 Jength, and the toes three before and one behind, you may conclude at once that it belongs to the tribe of Dentirostres. If, on 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. (446.) 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 (Parus), and is not perceptible in all the mock-birds (Orpheus). The long-legged thrushes (Crateropodine) have the bill entire. All these groups, nevertheless, have the feet so long, and so per-