Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/195

Rh The animal ranged over the whole of North America, from the frozen cliffs of Eschscholtz Bay as far south as the Isthmus of Darien—the Elephas americanus of Leidy and the E. Columbi of Falconer (E. texianus, Owen) being mere varieties of the same sort as those observable in the European mammoths, founded merely on the relative width and coarseness of the plates composing the grinders; while the E. Jacksoni of Billings merely supplies a slight variation in the form of the lower jaw.

Thus the mammoth ranged in ancient times over nearly the whole of the land of the northern hemisphere; and it is most important to note a singular fact in the distribution of the varieties with grinders composed respectively of narrow and wide plates. Just as in Euro-Asia the variety with its grinders composed of narrow plates has its headquarters in the north, and is replaced in Asia Minor by the variety with wide plates in its grinders (the E. armeniacus of Dr. Falconer), so in America is the narrow-plated form replaced in the southern parts of the continent by the E. Columbi. These differences may be the result of the use of different food in the northern and southern regions.

The next point to be considered is the relation of the mammoth to the Indian elephant on the other side of the barrier of deserts and mountains of Central Asia. On analyzing all the characters of the dentition, wo find that the ridge-formula and the succession of the teeth are the same, and that the last grinders are so alike that a lower molar of E. indicus has been figured by one of our most distinguished anatomists as that of a mammoth. In Dr. Falconer's classification, Elephas Columbi, E. indicus, and E. armeniacus are grouped together, their teeth being built on the same plan, "Colliculi approximati, machæridibus valde undulatis;" while next to them comes E. Primigenius, "Colliculi confertissimi, adamante valde attenuato, machæridibus vix undulatis." The differences expressed in these definitions seem to me to be merely of degree, and not of kind. Nor are the differences in the skeletons greater than those of the dentition. The possession of hair and wool depends, to a large extent, on climate, so that the covering of the Siberian mammoth cannot be taken to be a specific character.

On the present evidence the two seem to me to be so closely related that the mammoth may be taken as the ancestor of the Indian elephant; and it is highly probable that the latter has put on those trifling characters by which it is distinguished in the untold ages of its sojourn in the tropical forests of India—characters, be it remembered, of the same order as those observed in the dentition of Elephas Columbi of the warmer regions of North America, and the E. arme-