The analytical habit of mind which finds vent in the subdivision of species, is also exhibited in a tendency to break up large genera into a number of small ones, but in the present group this practice has the disadvantage of obscuring a broad distinction between the dominant types inhabiting respectively the old world and the new. The former, represented by the genus _Cervus_, has a brow-tine to the antlers; has the posterior portion of the nasal chamber undivided by the vertical plate of the vomer; and the upper ends only of the lateral metacarpals remain, whereas in all these particulars the typical American deer are exactly opposite. As there are objections to considering these characters as of family value, arising from the intermediate position of the circumpolar genera _Alces_ and _Rangifer_, as well as the water deer and the roe, a broader meaning is given to classification by retaining the comprehensive genera _Cervus_ and _Mazama_, and recognizing the subordinate divisions only as sub-genera. The one representative of _Cervus_ inhabiting America is the wapiti, or "elk" (_C. canadensis_), which is without doubt an immigrant from Asia by way of Alaska, and it may be of interest to state the grounds upon which this conclusion rests, as they afford an excellent example of the way in which such results are reached. It is an accepted truth in geographical distribution, that the portion of the earth in which the greatest number of forms differentiated from one type are to be found, is almost always the region in which that type had its origin. Now, out of about a dozen species and sub-species of wapiti and red deer to which names have been given, not less than eight are Asiatic, so that Asia, and probably its central portion, is indicated as the region in which the elaphine deer arose; in confirmation of which is the further fact that the antler characteristic of these deer seems to have originated from the same ancestral form as that which produced the sikine and rusine types, which are also Asiatic. From this centre the elaphines spread westward and eastward, resulting in Europe in the red deer, which penetrated southward into north Africa at a time when there was a land connection across the Mediterranean. In the opposite direction, the nearer we get to Bering's Straits the closer is the resemblance to the American wapiti, until the splendid species from the Altai Mountains (_C. canadensis asiaticus_), and Luehdorf's deer (_C. c. luehdorfi_) from Manchuria, are regarded only as sub-species of the eastern American form, which they approach through _C. c. occidentalis_ of Oregon and the northwestern Pacific Coast. This evidence is conclusive in itself, and is further confirmed by the geological record, from which we know that the land connection between Alaska and Kamtschatka was of Pliocene age, while we have no knowledge of the wapiti in America until the succeeding period.