. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds. Birds; Birds; 1887. 62 GENERAL ORNITHOLOGY. closely agreeing with one another in the peculiar sum of their physical characters. In compar- ison with other classes of Vertehrates, al
. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds. Birds; Birds; 1887. 62 GENERAL ORNITHOLOGY. closely agreeing with one another in the peculiar sum of their physical characters. In compar- ison with other classes of Vertehrates, all birds are much alike ; there is a less degrei^ of difference among them than that found among the members of any of the other classes of Verte- brates ; their likeness to each otlier being strong, and thoir kind of difference from any other Vertelirates being peculiar, makes them the "highly specialized" class they are recognized to 1)0. The structural difference between a humming-bird and an (jstricli, for example, is not greater in degree than that subsisting between the members of some of the orders of Reptiles ; whence some liold, with reason, that Birds should not form a class Aves, but an order, or at most a sub- class, of Sauropsida, and so be compared not with a class Reptilia collectively, but with other Sauropsidan or<lers, such as Chelonia (turtles), Sauria (lizards), Opliidia (serpents), etc. The practical convenience of starting with a "class" ^ces, however, is so great, that suoli classificatory value will probably long continue to be ascribed, as heretofore, to Birds conectively. I have spoken of Birds as a particular '' side-issue " or lateral branch of the Vertebrate '' tree of life "! hence it is not to be supposed that they are in tlie direct line of genealogical descent. Though they stand as a group nest below Mammals in the scale of evolution, it does not follow that Mammals were developed from any such creature as a Biid
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbirds, bookyear1887
