The Sea-cows are herbivorous aquatic animals living on the coasts or in the great rivers of several parts of the globe. Manatus (2 species) inhabits both shores of the Atlantic, one species ranging from the Gulf of Mexico to North Brazil, and ascending the Amazon far into the interior of the continent; while the other is found on the west coast of Africa. Halicore (2 species?), the Dugong, is peculiar to the Indian Ocean, extending from Mozambique to the Red Sea, thence to Western India and Ceylon, the Malay Archipelago and the north coast of Australia. Rytina (1 species), supposed to be now extinct, inhabited recently the North Pacific, between Kamschatka and Behring's Straits.
Fossil Sirenia.—Extinct species of Manatus have been found in the Post-pliocene deposits of Eastern North America from Maryland to Florida; and an extinct genus, Prorastomus, in some Tertiary deposits in the Island of Jamaica.
In Post-pliocene deposits in Siberia, remains of Rytina have been found; while several species of the extinct genus Halitherium, perhaps intermediate between Manatus and Halicore, have been found in the older Pliocene and Upper Miocene of France and Germany.
Order VII.—UNGULATA.
Family 43.—EQUIDÆ. (1 Genus, 8 Species.)
| General Distribution. | |||||
 | |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| Living Species. | |||||
| — — — — | — — — — | — 2. 3 — | 1. 2. 3 — | — — — — | — — — — |
| Extinct Species. | |||||
| 1. 2 — — | 1. 2. 3 — | 1. 2. 3. 4 | — — — — | 1 — 3 — | — — — — |
The Horses, Asses, and Zebras form a highly specialized group now confined to the Ethiopian and Palæarctic regions, but during the middle and later tertiaries having a very extensive range. The zebras (3 species) inhabit the greater part of the Ethiopian region, while the asses (4 species) are characteristic of the deserts of the Palæarctic region from North Africa and Syria to Western India, Mongolia, and Manchuria. The domestic horse is not known in a wild state, but its remains are found in recent deposits from Britain to the Altai Mountains, so that its disappearance is probably due to human agency.
Extinct Equidæ.—Extinct forms of this family are very numerous. The genus Equus occurs in Post-pliocene and Pliocene deposits in Europe, North America, and South America. In North America the species are most numerous. An allied genus Hipparion, having rudimentary lateral toes, is represented by several species in the Pliocene of North America, while in Europe it occurs both in the Older Pliocene and Upper Miocene. Various other allied forms, in which the lateral toes are more and more developed, and most of which are now classed in a distinct family, Anchitheridæ, range back through the Miocene to the Eocene period. A sufficient account of these has already been given in vol. i. chap. vi. p. 135, to which the reader is referred for the supposed origin and migrations of the horse.
Family 44—TAPIRIDÆ. (2 Genera? 6 Species.)
| General Distribution. | |||||
| |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — — — — | — — — 4 | — — — — |