GENERAL CHARACTERISTICS. 303 



by which they are inhabited. For instance, while the Palrearctic region, that is to 



say, the greater part of Europe and Asia north of the line of the Himalaya, is 



characterised by the sole possession of the capercaillie, and its abundance of grouse, 



buntings, etc., North America is the sole home of the turkey, while humming-birds 



are mainly characteristic of South and Central America, as are birds of paradise, 



lyre-birds, and cockatoos of the Australasian region. Many birds, especially some 



of the humming-birds, have indeed a very local distribution ; and, as might have 



been expected, the various groups of flightless Birds are now respectively confined 



to particular continents and islands. It would be impossible to pursue the subject 



further in the space available, but the reader will be enabled to gather many of 



the leading facts of avian distribution in the course of our description of the various 



groups. 



As regards their geological distribution, it may be mentioned that most of the 



birds from the Tertiary formations are more or less closely allied to existing types. 



When, however, we reach the antecedent Cretaceous (chalk) epoch, we find that at 



least several of the birds were furnished with teeth ; while in the still older Jurassic 



or Oolitic epoch the one definitely known bird {Arehaiopteryx) was not only 



furnished with teeth, but had a long tapering tail, and exhibited several other 



features indicative of reptilian affinity. While Birds present no sort of relationship 



to Mammals, they show manifest indications of being nearl}' allied to certain 



extinct groups of Reptiles ; but the nature of that relationship can be best indicated 



in our consideration of those groups. 



On no subject is there greater diversity of views among zoologists 

 Classification. . J ... wo 



than with regard to the classification of Birds ; scarcely any two 



ornithologists being in accord on this point. To a great extent this is owing to 



that structural uniformity among the members of the class to which reference has 



been already made, which renders it almost impossible to determine what features 



should be regarded as of primary importance. With such conflicting views it is 



inevitable that schemes of classification are to be counted almost by the dozen, and 



scarcely a year passes without one or more new ones being proposed. As it is 



unlikely that any one of these latter classifications will be permanently accepted, 



it has been thought advisable, in a popular work of the present nature, to revert to 



a modification of a scheme proposed some years ago by Dr. Sclater. Including 



certain extinct groups, the class, according to this scheme, may be divided into tin' 



following twenty-five groups, of which the first twenty-two may be reckoned 



orders — such orders, be it understood, being for the most part far less distinct from 



one another than are those of Mammals. 



Orders of Birds. 



1. Passeres — Perching Birds. 



2. Picarle — Woodpeckers, Cuckoos, Hornbills, etc. 



3. Psittaci — Parrots. 



4. Strides — Owls. 



5. Pandioxes — Ospreys. 



6. Accipitres — Eagles, falcons. Vultures, etc. 



