The geographical distribution of animals, with a study of the relations ...

;chap, viii.] BIRDS. . 161as indications of past changes in physical geography. A largeproportion of the remains belong to aquatic or wading types,and as these have now often a world-wide range, the occurrenceof extinct forms can have little bearing on our present inquiry.There are, however, a few interesting casesof extinct land-birdsbelonging to groups now quite strangers to the country in whichthey are found ; and others scarcely less interesting, in whichgroups now peculiar to certain areas are shown to have beenpreceded by allied species or genera of gigantic size.Palcearctic Region and N. India.—In the caves and otherPost-Pliocene deposits of these countries, the remains of birdsalmost all belong to genera now inhabiting the same districts.Almost the only exceptions are, the great auk and thecapercailzie, already mentioned as being found in the Danishmounds ; the latter bird, with Tetrao albus, in Italian cavernsand a species of pheasant (Phasianus) said to have occurred inthe Post- Pliocene of France, considerably west of the existingrange of the genus in a wild state.In the preceding Pliocene deposits, but few remains havebeen found, and all of existing genera but one, a gallinaceousbird (Gallus bravardi) allied to the domestic fowl and peacock.The Miocene beds of France and Central Europe have producedmany more remains ofbirds, but these, too, are mostly ofexisting European genera, though there are some notable exceptions.Along with forms undistinguishable from crows (Corvus),shrikes (Lanius),wagtails (Motacilla), and woodpeckers (Picus),are found remains allied to the Oriental edible-nest swift (Collocalia)and Trogon ; a parrot resembling the African genusPsittacus ; an extinct form Necrornis, perhaps allied to theplantain-eaters (Musophaga) ;Homalophus, doubtfully allied towoodpeckers, and Limnatornis to the hoopoes. The gallinaceousbirds arerepresented by three species of pheasants, somevery close to the domesticated species ; Palccoperdix allied to thepartridges ; and Palceortyx, small birds allied to the Americangenus Ortyx, but with larger wings. There are also species ofPterocles allied to living birds, and a small pigeon. There arenumerous living genera of Accipitres ; such as eagle {Aquila),