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Show 152 ST. FE. Oct. 1833. The occurrence of the fossil horse and of Mastodon augustidens in South America, is a much more remarkable circumstance than that ofthe animals mentioned above in the northern half of the continent; for if we divide America, not by the Isthmus of Panama, but by the southern part of Mexico,* in lat. 20°, where the great table-land presents an obstacle to the micrration of species, by affecting the climate, and by forming0 , with the exception of some valleys and of a fr'm ge of low land on the coast, a broad barrier; we shall then have two zoological provinces strongly contrasted with each other. Some few species alone have passed the barrier, and may be considered as wanderers, such as the puma, opossum, kinkajou, and peccari. The mammalogy of South America is characterized by possessing several species of the genera of llama, cavy (and the allied animals), tapir, peccari, opossum, anteater, sloth, and armadillo. If North America had possessed species of these genera proper to it, the distinction of the two provinces could not have been drawn ; but the presence of a few wanderers scarcely affects the case. North America, on 'the other hand, is characterized by its numerous rodents, t and by four genera of solid horned ruminants,t of which section the southern half does not possess a single species. whether from west to east, or the reverse. Perhap~, when we recollect how extraordinarily the Pachydermata abounded during the Tertiary epochs in the Old World, and that the representatives of these animals now only exist in that quarter, it may seem most probable that the migration took place from Asia to America. • This is the division followed by Lichtenstein, Swainson, and Richardson. The section from Vera Cruz to Acapulco, given by Humboldt in the Atlas to Polit. Essay on Kingdom of N. Spain, will show how immense a barrier the Mexican table-land forms. t Dr. Richardson (Report to Brit. Assoc., p. 157), talking of the identification of a Mexican animal with the Synetheres prehensilis, says, "We do not know with what propriety, but, if correct, it is, if not a solitary instance, at least very nearly so, of a rodent animal being common to North and South America." :j: Dicranoce1·us Jurcijet·, Capra Americana, Ovis montana, Bos Americana, and Moschatus.-Report to Brit. Assoc., p. 159. Oct. 1833. ZOOLOGICAL P ROVINCES. 153 This distinction of the two zoological provinces does not appear always to have existed. At the present day the order of Edentata is much more strongly developed in South America, than in any other part of the world : and concludin from the fossil remains, which were discovered at Bahi: Blanca, such must have been the case during a former epoch. In America, north of Mexico, not one of this order is no.w found: yet, .as is well k~own, the gigantic megalonyx, considered ~y Cuv1er as a species of Megatherium, has been found only m that country; and as it appears from recent observations,* the Megatherium Cuvierii itself likewise occurs there. Mr. Owen showed me the tibia of some large animal, which Sir Philip Egerton had purchased out of a collection. of the remains of the mastodon brought from North America. Mr. Owen says it certainly belongs to one of the Edentata, and it so closely resembles a bone which I found embedded, together with fragments of the great armadillo-like covering, in Banda Oriental, that it probabl! forms a species of the same genus. Lastly, among the fossils brought home by Captain Beechey from the N. W. coast, there was a cervical vertebra, which, when compared by Mr. Pentland t with the skeletons at Paris, was found to resemble that of the sloth and anteater more than that of any other animal, although having some points of essential difference. Of the Pachydermata four or five species are now found in America; but, as in the case of the Edentata, none are peculiar to the continent north of Mexico; and one alone seems to exist there as a wanderer. Yet the account of the multitude of bones of the mastodon and elephant, which have been discovered in the salt-licks of North America, is familiar to every one. The remains of the Mastodon giganteum have been found nowhere else; but those of the Eleplws primigenius are common to a large part of the • Ed. New Phil. Journal. July, 1828, p. 327. From a paper by Mr. Cooper in the Lyceum of Natural History of New York. i" See Dr. Buckland. Appendix to Beechey's Voyage, p. 597. |