The Classification and the Osteology of Birds

The class Aves. - Though this class contains a great number of specific forms, the structural modifications which they present are of comparatively little importance; any two birds which can be selected differing from one another far less than the extreme types of the Lacertilia, and hardly more than the extreme forms of the Chelonia, do. Hence the characters by which the following groups are separated appear almost insignificant when compared with those by which the divisions of the Reptilia are indicated. read more...