According to M. Gaudry, the ancestors of all the swine, with the hippopotami and extinct _Anthracotherium_, _Merycopotamus_, and many allied forms,--are the _Hyracotherium_ and _Pliolophus_, both found only in the London clay belonging to the Lower Eocene formation. FAMILY 48.--CAMELIDÆ. (2 Genera, 6 Species). GENERAL DISTRIBUTION. __________________________________/\__________________________________ / \ NEOTROPICAL| NEARCTIC |PALÆARCTIC | ETHIOPIAN | ORIENTAL | AUSTRALIAN SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS. -----------+-----------+-----------+-----------+-----------+------------ LIVING SPECIES. | | | | | 1. -- -- --|-- -- -- --|-- 2. 3 -- |-- -- -- --|-- -- -- --|-- -- -- -- | | | | | EXTINCT SPECIES. | | | | | 1. -- -- --|-- 2. 3. 4 |-- -- 3 -- |-- -- -- --|-- -- 3. --|-- -- -- -- | | | | | The Camels are an exceedingly restricted group, the majority of the species now existing only in a state of domestication. The genus _Camelus_ (2 species), is a highly characteristic desert form {217}of the Palæarctic region, from the Sahara to Mongolia as far as Lake Baikal. _Auchenia_ (4 species), comprehending the Llamas and Alpacas, is equally characteristic of the mountains and deserts of the southern part of South America. Two species entirely domesticated inhabit the Peruvian and Bolivian Andes; and two others are found in a wild state, the vicuna in the Andes of Peru and Chili (Plate XVI. vol. ii. p. 40), and the guanaco over the plains of Patagonia and Tierra del Fuego. _Extinct Camelidæ._--No fossil remains of camels have been found in Europe, but one occurs in the deposits of the Siwalik Hills, usually classed as Upper Miocene, but which some naturalists think are more likely of Older Pliocene age. _Merycotherium_, teeth of which have been found in the Siberian drift, is supposed to belong to this family. In North America, where no representative of the family now exists, the camel-tribe were once abundant. In the Post-pliocene deposits of California an _Auchenia_ has been found, and in those of Kansas one of the extinct genus _Procamelus_. In the Pliocene period, this genus, which was closely allied to the living camels, abounded, six or seven species having been described from Nebraska and Texas, together with an allied form _Homocamelus_. In the Miocene period different genera appear,--_Poebrotherium_, and _Protomeryx_,--while a _Procamelus_ has been found in deposits of this age in Virginia.