The geographical distribution of animals, with a study of the relations ...

146 DISTRIBUTION OF EXTINCT ANIMALS. [part ii.large size, especially among the Edentata and American familiesof Kodents, are additional proofs of a very high antiquity.Yet many of these cave animals are closely allied to thosewhich are found in North America in the Post-Pliocene depositsonly, so that we have no reason to suppose the cave-fauna tobe of much earlier date. But the great amount of organicchange it implies, must give us an enlarged idea of the vastperiods of time, as measured by years, which are included inthis, the most recent of all geological epochs.Pliocene Period of Temperate South America.—We have nowto consider the numerous remains of extinct animals found invarious deposits in the Pampas, and in Patagonia, and a few inBolivia. The age of these is uncertain; but as they are verysimilar to the cave-fauna, though containing a somewhat largerproportion of extinct genera and some very remarkable newforms, they cannot be very much older, and are perhaps bestreferred at present to the newer portion of the Plioceneformation.Carnivora.—The genus Machairodus orsabre-toothed tigers,represents the Felidae. There are several species of wolves(Canis) ; a weasel (Mustela) ;two bears of the Brazilian cavegenusArctotherium; and the extinct European genus Hyamarctos.Ungulata.—There are two species of Eqnus, found in thePampas, Chili, and Bolivia; two of Macrauchenia, an extraordinaryextinct group allied to the tapir and Palceothcrium, butwith the long neck, and general size of a camel. A secondspecies found on the highlands of Bolivia is much smaller.A more recent discovery, in Patagonia, is the almost perfectseries of teeth of a large animal named Homalodontotherium; andwhich is believed by Professor Flower, who has described it, tohave been allied to Rhinoceros, and still more to the MioceneHyracodon from North America ; and also to present someresemblances to Macrauchenia, and though much more remotely,to the curious genus Nesodon mentioned further on.The Artiodactyla, or even-toed Ungulates, are represented by aspecies of Picotyles, or peccary, found in the deposits of the