. 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. 62 GENEBAL OBNITHOLOGY. closely agreeing with one another in the peculiar sum of their physical characters. In compar- ison with other classes of Vertebrates, all bird
. 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. 62 GENEBAL OBNITHOLOGY. closely agreeing with one another in the peculiar sum of their physical characters. In compar- ison with other classes of Vertebrates, all birds are much alike; there is a less degree of diSJerenc'e among them than that found among the members of any of the other classes of Verte- brates : their likeness to each other being strong, and their kind of diiference from any other Vertebrates being peculiar, makes them the "highly specialized" class they are recognized to The structural difference between a humming-bird and an ostrich, for example, is not greater in degree than that subsisting between the members of some of the orders of KeptUes ; whence some hold, with reason, that Birds should not form a class Aves, bufau order, or at most a sub- class, of Sauropsida, and so be compared not with a class Beptilia collectively, but with other Sauropsidan orders, such as Chelonia (turtles), Sawria (lizards), Ophidia (serpents), etc. The practical convenience of starting with a " class" Aves, however, is so great, that such classificatory value will probably long continue to be ascribed, as heretofore, to Birds collectively. I have spoken of Birds as a particular " side-issue " or lateral branch of the Vertebrate " tree of life "J hence it is not to be supposed that they are in the direct line of genealogical descent. Though they stand as a group next below Mammals in the scale of evoliition, it does not follow that Mammals were developed from any such creature as a Bird has come t
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1894
