GEOGRAPHICAL DISTRIBUTION OF PLEISTOCENE MAMMALS.
A most interesting generalization has been educed from the mass of facts relating to the fossil Mammals of the later tertiaries—viz., the close correspondence between the fauna of those and of the present periods in the Europeo-Asiatic expanse of dry land. For here species continue to exist of nearly all those genera which are represented by pliocene and post-pliocene mammalian fossils of the same natural continent, and of the immediately adjacent island of Great Britain.
The bear has its haunts in both Europe and Asia ; the beaver of the Rhone and Danube represents the great 'rrogontherium ; the Lagomys and the tiger exist on both sides of the Himalayan mountain chain ; the hyena ranges through Syria and Hindostan ; the Bactrian camel typifies the huge Meiwcoth,erium, of the Siberian drift ; the elephant and rhinoceros are still represented in Asia, though now con fined to the south of the Himalayas. The true macacques are peculiar to Asia, and though most abundant in the southern parts of the continent and the Indian Archi pelago, also exist in Japan ; a closely-allied sub-genus (Innus) is naturalized on the rock of Gibraltar at the pre sent day. A fossil species of Macacus was associated with the elephant and rhinoceros in England during the period of the deposition of the newer pliocene fresh water beds. The more extraordinary extinct forms of Mammalia, called Elas motherium and Si•atherium, have their nearest existing pachy dennal and ruminant analogues in the same continent to which those fossils are peculiar. Cuvier places the Basmo there between the horse and rhinoceros. The existing four horned antelopes, like their gigantic extinct analogues, the Sivathere and Bramathere, are peculiar to India. It may be regarded as part of the same general concordance of geogra phical distribution, that the genus Hippopotamus, extinct in England, in Europe, and in Asia, should continue to be repre sented in Africa, and in none of the remoter continents of the earth—Africa also having its hymns, its elephant, its rhino ceros, and its great feline Carnivores. The discovery of
extinct species of Camelopardalis in both Europe and Asia, of which genus the sole existing representative is now, like the hippopotamus, confined to Africa, adds to the propriety of regarding the three continuous continental divisions of the Old World as forming, in respect to the geographical distribu tion of pliocene, post-pliocene, and recent mammalian genera, one great natural province. The only large edentate animal (Pangolin gigantesgue, Cuvier ; Macrotherium, Lartet) hitherto found in the tertiary deposits of Europe, manifests its nearest affinities to the genus Mani% which is exclusively Asiatic and African.
Extending the comparison between the existing and the latest of the extinct series of Mammalia to the continent of South America, it may be first remarked that with the exception of some carnivorous and cervine species, no repre sentatives of the above-cited mammalian genera of the Old World of the geographer have yet been found in South America. Buffon* long since enunciated a similar generali zation with regard to the existing species and genera of Mammalia ; it is almost equally true in respect of the fossil. Not a relic of an elephant, a rhinoceros, a hippopotamus, a bison, a hyEena, or a lagomys, has yet been detected in the caves or the more recent tertiary deposits of South America.
On the contrary, most of the fossil Mammalia from those formations are as distinct from the Europieo-Asiatic forms as they are closely allied to the peculiarly South American existing genera of Mammalia.
The genera Equus, Tapirus, and the still more ubiquitous Mastodon, form the chief, if not sole exceptions. The repre sentation of Equus during the pliocene period by distinct species in Asia (E. primigenius) and in South America (E. eurriclens), is analogous to the geographical distribution of the species of Tapirus at the present day.