The Artiodactyla, or even-toed Ungulates, are represented by a species of Dicotyles, or peccary, found in the deposits of the Pampas; by Auchenia, or llama, of which three extinct species inhabited Bolivia, in which country two allied but extinct genera, Palæolama and Camelotherium, have also been found. Three species of deer (Cervus), from the Pampas deposits, complete the list of Pliocene Ungulates.
Proboscidea.—The cave species of Mastodon is found also in the Pampas deposits, and another in the Andes of Chili and Bolivia.
Rodents.—These are not so numerous as in the caves. There are species of the existing genera, Kerodon and Cavia (Caviidæ); Lagostomus (Chinchillidæ); Ctenomys (Octodontidæ); Lepus (hare); Hesperomys and Oxymycterus (Muridæ); Arvicola, a genus not living in South America; and an extinct genus, Cardiodus. There is also a remarkable extinct form, Typotherium, larger than the capybara, and having affinities to Edentates and Ungulates. Three species have been found in the Pampas deposits.
Edentata.—These are as abundant and remarkable as in the cave deposits. Scelidotherium, Megatherium, Megalonyx, Glossotherium and Dasypus, have already been noticed as from the Brazilian caves. We have here, in addition, the huge Mylodon allied to the Megatherium, and the allied genera—Gnathopsis and Lestodon. We then come to the huge extinct armadillos, Glyptodon and Schistopleurum, the former consisting of numerous species, some of which were as large as an elephant. Another genus, Eutatus, is allied to the living three-banded armadillos; and a species of the existing genus Euphractus has been found in Bolivia.
Toxodontidæ.—There remain a number of huge animals rivalling the Megatherium in size, and forming the genera Toxodon and Nesodon, but whose position is doubtful. Several species have been found in the deposits of the Pampas and Patagonia. They are allied at once to Ungulates, Rodents, Edentates, and the aquatic Sirenia, in so puzzling a manner that it is impossible to determine to what order they belong, or whether they require a new order to be formed for their reception. Some are believed to date back to the Miocene period, and they indicate what strange forms may still be discovered, should any productive deposits be found in South America of middle Tertiary age.
Pliocene Mammalia of the Antilles.—These may be noticed here, as they are of special interest, proving the connection of the larger West Indian Islands with the Continent some time in the later Tertiary period. They consist of remains of two large animals belonging to the South American Chinchillidæ, found in cave deposits in the island of Anguilla, and forming two new genera, Amblyrhiza and Loxomylus; and remain allied to Megalonyx from Cuba, which have been named Megalocnus and Myomorphus.
Eocene fauna of South America.—The few remains yet discovered in the Tertiary deposits of the Pampas which are believed to be of Eocene age, are exceedingly interesting, because they show us another change in the scenery of the great drama of life; there being apparently a considerable resemblance, at this epoch, between South America and Europe. They consist of a large extinct feline animal, Eutemnodus; of Palæotherium and Anoplotherium, the well-known extinct Ungulates of the European Tertiaries, and which have never been found in North America; and of three genera of Rodents,—Theridromys, allied to Echimys, and found also in the Eocene and Miocene of France; Megamys, allied to the living Capromys of the Antilles, and also to Palæomys, an extinct form of the French Miocene; and a very large animal referred to Arvicola, a genus found also in the Pliocene deposits of South America, and abundant in the northern hemisphere. No Edentates have been found.
The resemblances of this fauna to that of Europe rather than to any part of America, are so strong, that they can hardly be accidental. We greatly want, however, more information on this point, as well as some corresponding evidences as to the condition of West and South Africa about the same epoch, before we can venture to speculate on their bearing as regards the early migrations of organic forms.
General Remarks on the Extinct Mammalian Fauna of the Old and New Worlds.—Leaving the more special applications of palæontological evidence to be made after discussing the relations of the existing fauna of the several regions, we propose here to indicate briefly, some of the more general deductions from the evidence which has now been laid before our readers.
The first, and perhaps the most startling fact brought out by our systematic review, is the very recent and almost universal change that has taken place in the character of the fauna, over all the areas we have been considering; a change which seems to be altogether unprecedented in the past history of the same countries as revealed by the geological record. In Europe, in North America, and in South America, we have evidence that a very similar change occurred about the same time. In all three we find, in the most recent deposits—cave-earths, peat-bogs, and gravels—the remains of a whole series of large animals, which have since become wholly extinct or only survive in far-distant lands. In Europe, the great Irish elk, the Machairodus and cave-lion, the rhinoceros, hippopotamus, and elephant;—in North America, equally large felines, horses and tapirs larger than any now living, a llama as large as a camel, great mastodons and elephants, and abundance of huge megatheroid animals of almost equal size;—in South America these same megatheroids in greater variety, numerous huge armadillos, a mastodon, large horses and tapirs, large porcupines, two forms of antelope, numerous bears and felines, including a Machairodus, and a large monkey,—have all become extinct since the deposition of the most recent of the fossil-bearing strata. This is certainly not a great while ago, geologically; and it is almost certain that this great organic revolution, implying physical changes of such vast proportions that they must have been due to causes of adequate intensity and proportionate range, has taken place since man lived on the earth. This is proved to have been the case in Europe, and is supported by much evidence both as regards North and South America.