In the above lists there are rather more Oriental than Palæarctic genera; but it must be remembered that most of the former are summer migrants only, or stragglers just entering the sub-region; whereas the great majority of the latter are permanent residents, and a large proportion of them range over the greater part of the Manchurian district. Many of those in the Oriental column should perhaps be omitted, as we have no exact determination of their range, and the limits of the regions are very uncertain. It must be remembered, too, that the Palæarctic genera of Sylviidæ, Paridæ, and Fringillidæ, are often represented by numerous species, whereas the corresponding Oriental genera have for the most part only single species; and we shall then find that, except towards the borders of the Oriental region the Palæarctic element is strongly predominant. Four of the more especially Oriental groups are confined to Japan, the southern {226}extremity of which should perhaps come in the Oriental region. The great richness of this sub-region compared with that of Siberia is well shown by the fact, that a list of all the known land-birds of East Siberia, including Dahuria and the comparatively fertile Amoor Valley, contains only 190 species; whereas Père David's catalogue of the birds of Northern China with adjacent parts of East Thibet and Mongolia (a very much smaller area) contains for the same families 366 species. Of the Siberian birds more than 50 per cent, are European species, while those of the Manchurian sub-region comprise about half that proportion of land-birds which are identical with those of Europe. Japan is no doubt very imperfectly known, as only 134 land-birds are recorded from it. Of these twenty-two are peculiar species, a number that would probably be diminished were the Corea to be explored. Of the genera, only nine are Indo-Malayan, while forty-three are Palæarctic.