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.
While there is not the least doubt that the smaller American deer had an origin identical with those of the old world, the exact point of their separation is not so clear. Two possibilities are open to choice: Mazama may be supposed to have descended from the group to which Blastomeryx belonged, this being a late Miocene genus from Nebraska, with cervine molars, but otherwise much like Cosoryx, which we have seen to be a possible ancestor of the prong-horn; or we may prefer to believe that the differentiation took place earlier in Europe or Asia, from ancestors common to both. But there is a serious dilemma. If we choose the former view, we must conclude that the deciduous antler was independently developed in each of the two continents, and while it is quite probable that approximately similar structures have at times arisen independently, it is not easy to believe that an arrangement so minutely identical in form and function can have been twice evolved. On the second supposition, we have to face the fact that there is very little evidence from palaeontology of the former presence of the American type in Eurasia. But, on the whole, the latter hypothesis presents fewer difficulties and is probably the correct one; in which case two migrations must have taken place, an earlier one of the generalized type to which Blastomeryx and Cosoryx belonged, and a later one of the direct ancestor of Mazama. There is little difficulty in the assumption of these repeated migrations, for evidence exists that during a great part of the last half of the Tertiary this continent was connected by land to the northwest with Asia, and to the northeast, through Greenland and Iceland, with western Europe.
The distinction between the two groups is well marked. All the Mazama type are without a true brow-tine to the antlers; the lower ends of the lateral metacarpals only remain; the vertical plate of the vomer extends downward and completely separates the hind part of the nasal chamber into two compartments; and with hardly an exception they have a large gland on the inside of the tarsus, or heel. The complete development of these characters is exhibited in northern species, and it has been beautifully shown that as we go southward there is a strong tendency to diminished size; toward smaller antlers and reduction in the number of tines; to smaller size, and finally complete loss of the metatarsal gland on the outside of the hind leg; and to the assumption of a uniform color throughout the year, instead of a seasonal change.
The two styles of antler which we recognize in the North American deer are too well known to require description. That characterizing the mule deer (Mazama hemionus) and the Columbia black-tailed deer (M. columbiana), seems never to have occurred in the east, nor south much beyond the Mexican border, and these deer have varied little except in size, although three subspecies have lately been set off from the mule deer in the extreme southwest.
The section represented by M. virginiana, with antlers curving forward and tines projecting from its hinder border, takes practically the whole of America in its range, and under the law of variation which has been stated, has proved a veritable gold mine to the makers of names. At present it is utterly useless to attempt to determine which of the forms described will stand the scrutiny of the future, and no more will be attempted here than to state the present gross contents of cervine literature. The sub-genus Dorcelaphus contains all the forms of the United States; of these, the deer belonging east of the Missouri River, those from the great plains to the Pacific, those along the Rio Grande in Texas and Mexico, those of Florida, and those again of Sonora, are each rated as sub-species of virginiana; to which we must add six more, ranging from Mexico to Bolivia. One full species, M. truei, has been described from Central America, and another rather anomalous creature (M. crookii), resembling both white-tail and mule deer, from New Mexico.
The other sub-genera are Blastoceros, with branched antlers and no metatarsal gland; Xenelaphus, smaller in size, with small, simply forked antlers and no metatarsal gland; Mazama, containing the so-called brockets, very small, with minute spike antlers, lacking the metatarsal and sometimes the tarsal gland as well. The last three sub-genera are South American and do not enter the United States. Another genus, Pudua, from Chili, is much like the brockets, but has exceedingly short cannon bones, and some of the tarsal bones are united in a manner unlike other deer. In all, thirty specific and sub-specific names are now carried on the roll of Mazama and its allies.
Attention has already been directed to the parallelism between the course of progress from simple to complex antlers in the development of the deer tribe, and the like progress in the growth of each individual, and to the further fact that all the stages are represented in the mature antlers of existing species. But a curious result follows from a study of the past distribution of deer in America. At a time when the branched stage had been already reached in North America, the isthmus of Panama was under water; deer were then absent from South America and the earliest forms found fossil there had antlers of the type of M. virginiana. The small species with simple antlers only made their appearance in later periods, and it follows that they are descended from those of complex type. This third parallel series, therefore, instead of being direct as are the other two, is reversed, and the degeneration of the antler, which we have seen taking place in the southern deer, has followed backward on the line of previous advance, or, in biological language, appears to be a true case of retrogressive evolution—representing the fossil series, as it were, in a mirror.
The reindeer-caribou type, of the genus Rangifer, agrees with American deer in having the vertical plate of the vomer complete, and in having the lower ends of the lateral metacarpals remaining, but, like Cervus, it has a brow-tine to the antlers. Of its early history we know nothing, for the only related forms which have yet come to light are of no great antiquity, being confined to the Pleistocene of Europe as far south as France, and are not distinguishable from existing species. Until recently it has been supposed that one species was found in northern Europe and Asia, and two others, a northern and a southern, in North America, but lately the last two have been subdivided, and the present practice is to regard the Scandinavian reindeer (Rangifer tarandus) as the type, with eight or nine other species or sub-species, consisting of the two longest known American forms, the northern, or barren-ground caribou (R. arcticus); the southern, or woodland (R. caribou); the three inhabiting respectively Spitzbergen, Greenland and Newfoundland, and still more lately four more from British Columbia and Alaska. The differences between these are not very profound, but they seem on the whole to represent two types: the barren-ground, small of size, with long, slender antlers but little palmated; and the woodland, larger, with shorter and more massive antlers, usually with broad palms. There is some reason to believe that both these types lived in Europe during the interglacial period, the first-named being probably the earlier and confined to western Europe, while the other extended into Asia. The present reindeer of Greenland and Spitzbergen seem to agree most closely with the barren-ground, while the southern forms are nearest to the woodland, and these are said to also resemble the reindeer of Siberia. It is, therefore, not an improbable conjecture that there were two migrations into America, one of the barren-ground type from western Europe, by way of the Spitzbergen land connection, and the other of the woodland, from Siberia, by way of Alaska.
Little more can be said, perhaps even less, of the other circumpolar genus, Alces, known in America as "moose," and across the Atlantic as "elk." It also is of mixed character in relation to the two great divisions we have had in mind, but in a different way from
