The other families which are well developed in the Palæarctic regions, are, the Staphylinidæ or rove-beetles, Silphidæ or burying-beetles, Histeridæ or mimic-beetles, Nitidulidæ, Aphodiidæ, Copridæ (especially in South Europe), Geotrupidæ or dung-beetles, Melolonthidæ or chafers, Elateridæ or click-beetles, the various families of Malacoderms and Heteromera, especially Pimeliidæ in the Mediterranean sub-region, Curculionidæ or weevils, the Phytophaga or leaf-eaters, and Cocinellidæ or lady-birds. The number of species of Coleoptera in the western part of the Palæarctic region is about 15,000, and there are probably not more than 2,000 to add to this number from Siberia, Japan, and North China; but were these countries as well explored as Europe, we may expect that they would add at least 5,000 to the number above given, raising the Palæarctic Coleopterous fauna to 20,000 species. As the total number of species at present known to exist in collections is estimated (and perhaps somewhat over-estimated) at 70,000 species, we may be sure that were the whole earth as thoroughly investigated as Europe, the number would be at least doubled, since we cannot suppose that Europe, with the Mediterranean basin, can contain more than one-fifth of the whole of the Coleoptera of the globe. Of the other orders of insects we here say nothing, because in their case much more than in that of the Coleoptera and Lepidoptera, is the disproportion enormous between our knowledge of the European fauna and that of almost all the rest of the globe. {190}They are, therefore, at present of comparatively little use for purposes of geographical distribution, even were it advisable to enter into the subject in a work which will, perhaps, be too much overburdened with details only of interest to specialists.