The Tapirs form a small group of animals whose discontinuous distribution plainly indicates their approaching extinction. For a long time only two species were known, the black American, and the white-banded Malay tapir, the former confined to the equatorial forests of South America, the latter to the Malay peninsula, Sumatra, and Borneo (Plate VIII. vol. i. p. 337). Lately however another, or perhaps two distinct species (or according to Dr. J. E. Gray, four!) have been discovered in the Andes of New Granada and Ecuador, at an elevation of from 8,000 to 12,000 feet; while one or perhaps two more, forming the allied genus Elasmognathus, have been found to inhabit Central America from Panama to Guatemala.
Extinct Tapirs.—True tapirs inhabited Western Europe, from the latest Pliocene back to the earliest Miocene times; while they only occur in either North or South America in the Post-pliocene deposits and caves. The singular distribution of the living species is thus explained, since we see that they are an Old World group which only entered the American continent at a comparatively recent epoch. An ancestral form of this group—Lophiodon—is found in Miocene and Eocene deposits of Europe and North America; while a still more ancient form of large size is found in the Lower Eocene of France and England, indicating an immense antiquity for this group of Mammalia. There are many other extinct forms connecting these with the Palæotheridæ, already noticed in chapter vi. (vol. i. pp. 119-125).
Family 45.—RHINOCEROTIDÆ. (1 Genus, 9 Species.)
| General Distribution. | |||||
 | |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| Living Species. | |||||
| — — — — | — — — — | — — — — | 1. 2. 3 — | — — 3. 4 | — — — — |
| Extinct Species. | |||||
| — — — — | 1. 2 — — | 1. 2. 3. 4 | — — — — | 1 — 3 — | — — — — |
Living Rhinoceroses are especially characteristic of Africa, with Northern and Malayan India. Four or perhaps five species, all two-horned, are found in Africa, where they range over the whole country south of the desert to the Cape of Good Hope. In the Oriental region there are also four or five species, which range from the forests at the foot of the Himalayas eastwards through Assam, Chittagong, and Siam, to Sumatra, Borneo and Java. Three of these are one-horned, the others found in Sumatra, and northwards to Pegu and Chittagong, two-horned. The Asiatic differ from the African species in some dental characters, but they are in other respects so much alike that they are not generally considered to form distinct genera. In his latest catalogue however (1873), Dr. Gray has four genera, Rhinoceros (4 species), and Ceratorhinus (2 species), Asiatic; Rhinaster (2 species), and Ceratotherium (2 species), African.
Extinct Rhinocerotidæ.—Numerous species of Rhinoceros ranged over Europe and Asia from the Post-pliocene back to the Upper Miocene period, and in North America during the Pliocene period only. The hornless Acerotherium is Miocene only, in both countries. Other genera are Leptodon from Greece, and Hyracodon from Nebraska, both of Miocene age. More than 20 species of extinct rhinoceroses are known, and one has even been found at an altitude of 16,000 feet in Thibet.
Family 46.—HIPPOPOTAMIDÆ. (1 Genus, 2 Species.)
| General Distribution. | |||||
| |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| Living Species. | |||||
| — — — — | — — — — | — — — — | 1. 2. 3 — | — — — — | — — — — |
| Extinct Species. | |||||
| — — — — | — — — — | 1. 2 — — | — — — — | 1 — 3 — | — — — — |
The Hippopotamus inhabits all the great rivers of Africa; a distinct species of a smaller size being found on the west coast, and on some of the rivers flowing into Lake Tchad.
Fossil Hippopotami.—Eight extinct species of Hippopotamus are known from Europe and India, the former Post-pliocene or Pliocene, the latter of Upper Miocene age. They ranged as far north as the Thames valley. An extinct genus from the Siwalik Hills, Merycopotamus, according to Dr. Falconer connects Hippopotamus with Anthracotherium, an extinct form from the Miocene of Europe, allied to the swine.