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celebrated for its power of ejecting a terribly offensive liquid, the odour of which is almost intolerable. The skunks are nocturnal animals, and are generally marked, as in the species represented, with conspicuous bands and patches of white. This enables them to be easily seen at night, and thus serves to warn larger animals not to attack them. To the left is the curious little jumping mouse (Jaculus hudsonius), the American representative of the Palaearctic jerboa. Climbing up a tree on the left is the tree porcupine (Erethizon dorsatus), belonging to the family Cercolabidae, which represents, on the American continent, the porcupines of the Old World. In the background is the elk or moose (Alces americanus), perhaps identical with the European elk, and the most striking inhabitant of the northern forests of America, as the bison is of the prairies. Birds.—Although the Canadian sub-region possesses very few resident birds, the numbers which breed in it are perhaps greater than in the other sub-regions, because a large number of circumpolar species are found here exclusively. From a comparison of Mr. Allen's tables it appears, that more than 200 species are regular migrants to Canada in the breeding season, and nearly half of these are land-birds. Among them are to be found a considerable number of genera of the American families Tyrannidae and Mniotiltidae, as well as the American genera Sialia, Progne, Vireo, Cistothorus, Junco, Pipilo, Zonotrichia, Spizella, Melospiza, Molothrus, Agelarus, Cyanura, Sphyrapicus, and many others; so that the ornithology of these northern regions is still mainly Nearctic in character. Besides these, it has such specially northern forms as Surnia (Strigidae); Picoides (Picidae); Pinicola (Fringillidae); as well as Leucosticte, Plectrophanes, Perisoreus, and Lagopus, which extend further south, especially in the middle sub-region. No less than 212 species of birds have been collected in the new United States territory of Alaska (formerly Russian America), where a humming-bird (Selasphorus rufus) breeds. The great majority of these are typically American, including such forms as Colaptes, Helminthophaga, Siurus, Dendraeca, Myiodioctes, Passerculus, Zonotrichia, Junco, Spizella, Melospizpa, Passerella, Scoleophagas, Pediocetes, and Bonasa;
together with many northern birds common to both continents. Yet a few Palaearctic forms, not known in other parts of the sub-region, appear here. These are Budytes flava, Phylloscopus kennicottii, and Pyrrhula coccinea, all belonging to genera not occurring elsewhere in North America. Considering the proximity of the district to North-east Asia, and the high probability that there was an actual land connection at, and south of, Behring's Straits, in late Tertiary times, it is somewhat remarkable that the admixture of Palaearctic and Nearctic groups is not greater than it is. The Palaearctic element, however, forms so small a portion of the whole fauna, that it may be satisfactorily accounted for by the establishment of immigrants since the Glacial period. The great interest felt by ornithologists in the discovery of the three genera above-named, with a wren allied to a European species, is an indication that the faunas even of the northern parts of the Nearctic and Palaearctic regions are, as regards birds, radically distinct. It may be mentioned that the birds of the Aleutian Isles are also, so far as known, almost wholly Nearctic. The number of land-birds known from Alaska is 77; and from the Aleutian Isles 16 species, all of which, except one, are North American. Reptiles.—These are comparatively few and unimportant. There are however five snakes and three tortoises which are limited to Canada proper; while further north there are only Amphibia, represented by frogs and toads, and a salamander of the genus Plethodon. Fishes.—Most of the groups of fresh-water fish of the Nearctic region are represented here, especially those of the perch, salmon, and pike families; but there seem to be few or no peculiar genera. Insects.-These are far less numerous than in the more temperate districts, but are still tolerably abundant. In Canada there are 53 species of butterflies, viz., Papilionidae, 4; Pieridae, 2; Nymphalidae, 21; Satyridae, 3; Lycaenidae 16, and Hesperidae 7. Most of these are, no doubt, found chiefly in the southern parts of Canada. That Coleoptera are pretty numerous is shown, by more than 800 species having been collected on the shores of Lake Superior; 177 being Geodephaga and 39 Longicorns.
Greenland.—This great arctic island must be considered as belonging to the Nearctic region, since of its six land mammals, three are exclusively American (Myodes torquatus, Lepus glacialis, and Ovibos moschatus), while the other three (Vulpes lagopus, Ursus maritimus, and Rangifer tarandus) are circumpolar. Only fourteen land-birds are either resident in, or regular migrants to the country; and of these two are European (Haliaetus albicilla, and Falco peregrinus), while three are American (Anthus ludovicianus, Zonotrichia leucophrys, and Lagopus rupestris), the rest being arctic species common to both continents. The waders and aquatics (49 in number) are nearly equally divided between both continents; but the land-birds which visit Greenland as stragglers are mostly American. Yet although the Nearctic element somewhat preponderates, Greenland really belongs to that circumpolar debateable land, which is common to the two North Temperate regions.
Concluding remarks—We have already discussed pretty fully, though somewhat incidentally, the status and relations of the Nearctic region; first in our chapter on Zoological regions, then in our review of extinct faunas, and lastly in the earlier part of this chapter. It will not therefore be necessary to go further into the question here; but we shall, in our next chapter, give a brief summary of the general conclusions we have reached as to the past history and mutual zoological relations of all the great divisions of the earth.