Geology gives a wider range to the horse and elephant kinds than was cognizant to the student of living species only. The existing Equidæ and Elephantidæ properly belong, or are limited, to the Old World; and the elephants to Asia and Africa, the species of the two continents being quite distinct. The horse, as Buffon remarked, carried terror to the eye of the indigenous Americans, viewing the animal for the first time, as it proudly bore their Spanish conqueror. But a species of Equus coexisted with the Megatherium and Megalonyx in both South and North America, and perished apparently with them, before the human period. Elephants are dependent chiefly upon trees for food. One species now finds conditions of existence in the rich forests of tropical Asia; and a second species in those of tropical Africa. Why, we may ask, should not a third be living at the expense of the still more luxuriant vegetation watered by the Orinoco, the Essequibo, the Amazon, and La Plata, in tropical America? Geology tells us that at least two kinds of elephant (Mastodon Andium and Mastodon Humboldtii) formerly did derive their subsistence, along with the great Megatheroid beasts, from that abundant source. Nay, more; at least two kinds of elephant (Mastodon ohioticus and Elephas texianus) existed in the warm and temperate latitudes of North America. Twice as many species of mastodon and elephant, distinct from all the others, roamed in Pliocene times in the same latitude of Europe. At a later or Pleistocene period, a huge elephant, clothed with wool and hair, obtained its food from hardy trees, such as now grow in the 65th degree of north latitude; and abundant remains of this Elephas primigenius (as it has been prematurely called, since it was the last of the British elephants) have been found in temperate and high northern latitudes in Europe, Asia, and America. This, like other Arctic animals, was peculiar in its family for its longitudinal range. The musk buffalo was its contemporary in England and Europe, and still lingers in the northernmost parts of America. I have received evidences of elephantine species from China and Australia, proving the proboscidian pachyderms to have been the most cosmopolitan of hoofed herbivorous quadrupeds. Geology extends the geographical range of the sloths and armadillos from South to North America; but the deductions from recent rich discoveries of huge terrestrial forms of sloth, of gigantic armadillos, and large anteaters go to establish the fact that these peculiar features of the order Bruta have ever been, as they are now, peculiar to America; that several genera, including the larger species, have perished; and that the range of their still existing diminutive representatives has been reduced to the southern division of the New World.