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The Bisons (Fig. 33) are still common to the Nearctic and Palrearctic Region, though now nearly extinct in both hemispheres.
Rodents are very numerous in the Nearctic Region. According to the tables here used, which have been compiled from Flower and Lydekker's text-book of
mammals, out of a total number of twenty-eight genera, thirteen are endemic. One of these, Raplodon, a small animal resembling the Prairie-dog in its habits, and found only west of the Rocky Mountains, forms a distinct family.
The Carnivora are also well represented, especially the genera of Cats, Dogs, Bears, and Weasels, all of which, however, are widely spread. The only endemic genus is that formed for the reception of the American Badger (Taxidea), which differs from its European ally in certain anatomical features.
In contradistinction to the Neotropical Region, the Insectivora are abundant in the Nearctic; there are no less
than four genera of Moles met with, three of which are peculiar.
Amongst them is the remarkable Star-nosed Mole (Condylura cristata) which carries a ring of riband-like appendages at the end of its snout. These serve, no doubt, as a sensitive organ (see Fig. 34).
Finally, the Bats are neither very numerous nor of great importance; only one genus (Antrozous), containing one species, being peculiar out of a total of nine.
Summarizing, therefore, we find the Nearctic Region to be characterized by the exclusive possession of only two families of Mammals—namely, Antilocapridse (the Prongbucks) and Haplodontidse (the Haplodonts), and by the presence of sixty-six genera, of which twenty-one are restricted within its boundaries. On the other hand, in addition to the two orders already mentioned, Monotremes and Primates, the following important families are absent in the Nearctic Region, although fairly well spread over the Old World:—
SuidsB (Swine). Hyeenidse (Hyenas).
Equidse (Horses). Erinaceidae (Hedgehogs).
Myoxidae (Dormice). Pteropodidse (Fruit-eating Bats).
Viverridae (Civets). Rhinolophidee (Leaf-nosed Bats).
That some of these families did, however, at one time exist on the North American continent has been shown by recent palaeontological discoveries.
Section III.—Sub-division Of The Nearctic Region
The recent work of American naturalists, more especially that of Merriam (2) and of Allen (1), has greatly increased our knowledge of the mammals of North America and of their distribution. These naturalists have further shown that the Sub-regions adopted by Wallace in his well-known text-book on geographical distribution are not altogether supported by the facts now known to us.
Mr. Allen, in his paper on the distribution of North
American mammals, first of all excludes from what he terms the North American Region the extreme northern parts of that continent. He considers that the Arctic portion of that continent, namely, that beyond the limit of arboreal vegetation, forms, together with the similar part of the Old World, a separate Region, or, as he terms it, "the Arctic Realm."
Furthermore, the southern part of North America south of the Mexican tableland, together with the lowlying country of Mexico on either flank, he assigns to the American Tropical Realm. The remainder of the continent, combined with the great mass of Europe and Asia, forms, according to this author, the North Temperate Realm. This scheme of division does not differ essentially from that of Mr. Allen. The Arctic portion of North America forms, no doubt, as Mr. Allen puts it, "part of a homogeneous hyperborean faunal area of circumpolar distribution."
Mr. Allen's American Tropical Realm has already been treated of in the chapter of this volume dealing with the Neotropical Region (see p. 52). There remains,therefore, Mr. Allen's North American Region, which nearly corresponds to the Nearctic Region of our scheme of classification. Mr. Allen divides his North American Region into two Subregions—the Cold Temperate and the Warm Temperate, the two latter falling into two provinces, a Humid or Eastern and an Arid or Western. Proceeding further, he divides the Humid province into two sub-provinces, namely, an Apalachian or Northern and an Austro-riparian or Southern. The Arid or Western province is also separated into two sub-provinces—the Campestrian or Northern and the Sonoran or Southern, and, besides this, the subprovinces are divided into various minor divisions termed districts and faunas.
It will be sufficient for our present purpose to divide the North American or Nearctic Region into three Subregions; these may be termed, (1) the Canadian or Cold Sub-region, (2) the Western or Humid Sub-region, and (3) the Eastern or Arid Sub-region.
Mr. Wallace has recognized four Sub-regions in the Nearctic Region. His Canadian Sub-region corresponds fairly well to the Canadian or North Temperate of Mr. Allen, except for the fact that it has not been made by Mr. Wallace to extend southward down the mountain ranges. The Alleghany Sub-region of Mr. Wallace, again, practically corresponds to the "Humid " of Mr. Allen. The two others, the Rocky Mountain and Californian, correspond to Mr. Allen's "Arid," the Californian Sub-region being composed of a narrow strip of coast country between the Sierra Nevada and the sea, and extending from Queen Charlotte's Sound in the north to the south-western corner of California. The differences, therefore, between Mr. Wallace's and Mr. Allen's views are not so fundamental as one would gather from the critical remarks of the latter author.
The boundaries of the Sub-regions here adopted will be best understood by reference to the accompanying map (Plate VI., p. 176).
The Canadian or Cold Sub-region embraces the whole of the northern portion of North America, including Greenland. The southern limit of this Sub-region commences, on the Atlantic side, on the coast of Maine, in the neighbourhood of Augusta, and thence runs to Quebec and through the Great Lakes. Further west it is bounded