Species ofMustelahave been found in the Pliocene of France and of South America; andLutrain the Pliocene of North America.
In the Miocene deposits of Europe several species ofMustelaandLutrahave been found; with the extinct generaTaxodon,Potamotherium, andPalæomephitis; as well asPromephitisin Greece.
In the Upper Miocene of the Siwalik Hills species ofLutraandMellivoraare found, as well as the extinct generaEnhydrionandUrsitaxus.
The family appears to have been unknown in North America during the Miocene period.
Family30.—PROCYONIDÆ. (4 Genera, 8 Species.)
The Procyonidæ are a small, but very curious and interesting family of bear-like quadrupeds, ranging from British Columbia and Canada on the north, to Paraguay and the limits of the tropical forests on the south.
The Racoons, forming the genusProcyon, are common all over North America; a well-marked variety or distinct species inhabiting the west coast, and another, most parts of South America. The genusNasua, or the coatis (5 species?), extends from Mexico and Guatemala to Paraguay. The curious arboreal prehensile-tailed kinkagou (Cercoleptes candivolvus) is also found in Mexico and Guatemala, and in all the great forests of Peru and North Brazil.Bassaris(2 species), a small weasel-like animal with a banded tail, has been usually classed with the Viverridæ or Mustelidæ, but is now found to agree closely in all important points of internal structure with this family. It is found in California, Texas, and the highlands of Mexico, and belongs therefore as much to the Nearctic as to the Neotropical region. A second species has recently been described by Professor Petersfrom Coban in Guatemala, in which, country it has also been observed by Mr. Salvin.
Fossil Procyonidæ.—A species ofNasuahas been found in the bone caves of Brazil, and aProcyonin the Pliocene or Post-pliocene deposits of Illinois and Carolina.
Family31.—ÆLURIDÆ. (2 Genera, 2 Species.)
The Panda (Ælurus fulgens), of the forest regions of the Eastern Himalayas and East Thibet, a small cat-like bear, has peculiarities of organization which render it necessary to place it in a family by itself. (Plate VII. vol. i. p. 331). An allied genus,Æluropus, a remarkable animal of larger size and in colour nearly all white, has recently been described by Professor Milne-Edwards, from the mountains of East Thibet; so that the family may be said to inhabit the border lands of the Oriental and Palæarctic regions. These animals have their nearest allies in the coatis and bears.
Family32.—URSIDÆ. (5 Genera, or Sub-genera, 15 Species.)
The Bears have a tolerably wide distribution, although they are entirely absent from the Australian and Ethiopian, and almost so from the Neotropical region, one species only being found in the Andes of Peru and Chili. They comprise the following groups, some of which are doubtfully ranked as genera.
Thalassarctos, the polar bear (1 species) inhabiting the Arctic regions;Ursus, the true bears (12 species), which range overall the Nearctic and Palæarctic regions as far as the Atlas Mountains, the Indo-Chinese sub-region in the mountains, and to Hainan and Formosa;Helarctos, the Malay or sun-bear (1 species) confined to the Indo-Malayan sub-region;MelursusorProchilus, the honey-bear (1 species), confined to the first and second Oriental sub-regions, over which it ranges from the Ganges to Ceylon; andTremarctos, the spectacled bear—commonly known asUrsus ornatus—which is isolated in the Andes of Peru and Chili, and forms a distinct group.
Fossil Ursidæ.—Two bears (Ursus spelæusandU. priscus) closely allied to living species, abound in the Post-tertiary deposits of Europe; and others of the same age are found in North America, as well as an extinct genus,Arctodus.
Ursus arvernensisis found in the Pliocene formation of France, and the extinct genusLeptarchusin that of North America.
Several species ofAmphicyon, which appears to be an ancestral form of this family, are found in the Miocene deposits of Europe and N. India; whileUrsusalso occurs in the Siwalik Hills and Nerbudda deposits.
Family33.—OTARIIDÆ (4 Genera, 8 Species.)
The Otariidæ, or Eared Seals, comprehending the sea-bears and sea-lions, are confined to the temperate and cold shores of the North Pacific, and to similar climates in the Southern Hemisphere, where the larger proportion of the species are found. They are entirely absent from the North Atlantic shores. Mr. J. A. Allen, in his recent discussion of this family (Bull. Harvard Museum) divides them into the following genera:—
Otaria(1 species), Temperate South America, from Chili to La Plata;Callorhinus(1 species), Behring's Straits and Kamschatka;Arctocephalus(3 species), temperate regions of theSouthern Hemisphere;Zalophus(2 species), North Pacific, from California to Japan, and the shores of Australia and New Zealand;Eumetopias(1 species), Behring's Straits and California.
Fossil Otariidæ.—Remains supposed to belong to this family have been found in the Miocene of France.
Family34.—TRICHECHIDÆ. (1 Genus, 1 Species.)
The Morse, or Walrus (Trichecus rosmarus), which alone constitutes this family, is a characteristic animal of the North Polar regions, hardly passing south of the Arctic circle except on the east and west coasts of North America, where it sometimes reaches Lat. 60°. It is most abundant on the shores of Spitzbergen, but is not found on the northern shores of Asia between Long. 80° and 160° E., or on the north shores of America from 100° to 150° west.
Its remains have been found fossil in Europe as far south as France, and in America as far as Virginia; but the small fragments discovered may render the identification uncertain.
Family35.—PHOCIDÆ. (13 Genera, 21 Species.)
The earless or true Seals are pretty equally divided between the Northern and Southern Hemispheres, frequenting almost exclusively the temperate and cold regions, except two species said to occur among the West Indian islands. The genusPhocaand its close allies, as well asHalichœrusandPelagius, arenorthern; whileStenorhynchusandMorunga, with their allies, are mostly southern. The genera admitted by Dr. Gray in his catalogue are as follows:—
Callocephalus(3 species), Greenland, North Sea, also the Caspian Sea, and Lakes Aral and Baikal;Pagomys(2 species), North Sea, North Pacific, and Japan;Pagophilus(2 species), North Pacific and North Atlantic;Halicyon(1 species), North West coast of America;Phoca(2 species), North Atlantic and North Pacific, Japan;Halichœrus(1 species), Greenland, North Sea, and Baltic;Pelagius(2 species), Madeira, Mediterranean, Black Sea;Stenorhynchus(1 species), Antarctic Ocean, Falkland Islands, New Zealand;Lobodon(1 species), Antarctic Ocean;Leptonyx(1 species), Antarctic Ocean, South Australia, East Patagonia;Ommatophoca(1 species), Antarctic Ocean;Morunga(2 species), California, Falkland Islands, Temperate regions of Southern Ocean;Cystophora(2 species), North Atlantic, Antilles.
Fossil Seals.—Remains of living species of seals have been found in Post-tertiary deposits in many parts of Europe and in Algeria, as well as in New Zealand.Pristiphoca occitanais a fossil seal from the Pliocene of Montpellier, while a species ofPhocais said to have been found in the Miocene deposits of the United States.
General Remarks on the Distribution of the Carnivora.
Terrestrial Carnivora.—For the purposes of geographical distribution, the terrestrial and aquatic Carnivora differ too widely to be considered in one view, their areas being limited by barriers of a very different nature. The terrestrial Carnivora form a very extensive and considerably varied group of animals, having, with the doubtful exception of Australia, a world-wide distribution. Yet the range of modification of form is not very great, and the occurrence of three families consisting of but one species each, is an indication of a great amount of recent extinction. One of the most marked features presented by this group is its comparative scarcity in the Neotropical region, only four families being represented there (not counting the Ursidæ, which has only one Andean species), and both genera and species are few in number. Even the Procyonidæ, which are especially SouthAmerican, have but two genera and six species in that vast area. We might therefore, from these considerations alone, conclude that Carnivora are a development of the northern hemisphere, and have been introduced into the Neotropical region at a comparatively recent epoch. The claim of the Nearctic region to be kept distinct from the Palæarctic (with which some writers have wished to unite it) is well maintained by its possession of at least six species ofMephitis, or skunk, a group having no close allies in any other region,—and the generaProcyonandBassaris,—for the latter, ranging from the high lands of Guatemala and Mexico to Texas and California, may be considered a Nearctic rather than a Neotropical form. In the other families, the most marked feature is the total absence of Ursidæ from the Ethiopian region. The great mass of the generic forms of Carnivora, however, are found in the Oriental and Ethiopian regions, which possess all the extensive group of Viverridæ (except a few species in the fourth Palæarctic sub-region) and a large number of Felidæ and Mustelidæ.
Aquatic Carnivora.—The aquatic Carnivora present no very marked features of distribution, except their preference for cold and temperate rather than tropical seas. Their nearest approximation to the terrestrial group, is supposed to be that of the Otariidæ to the Ursidæ; but this must be very remote, and the occurrence of both seals and bears in the Miocene period, shows, that until we find some late Secondary or early Tertiary formation rich in Mammalian remains, we are not likely to get at the transition forms indicating the steps by which the aquatic Carnivora were developed. The most interesting special fact of distribution to be noticed, is the occurrence of seals, closely allied to those inhabiting the northern seas, in the Caspian, Lake Aral, and Lake Baikal. In the case of the two first-named localities there is little difficulty, as they are connected with the North Sea by extensive plains of low elevation, so that a depression of less than 500 feet would open a free communication with the ocean. At a comparatively recent epoch, a great gulf of the Arctic ocean must have occupied the valley of the Irtish, and extended to the Caspian Sea; till the elevation of the Kirghiz Steppes cut off thecommunication with the ocean, leaving an inland sea with its seals. Lake Baikal, however, offers much greater difficulties; since it is not only a fresh-water lake, but is situated in a mountain district nearly 2,000 feet above the sea level, and entirely separated from the plains by several hundred miles of high land. It is true that such an amount of submergence and elevation is known to have occurred in Europe so recently as during the Glacial period; but Lake Baikal is so surrounded by mountains, that it must at that time have been filled with ice, if at anything like its present elevation. Its emergence from the sea must therefore have taken place since the cold epoch, and this would imply that an enormous extent of Northern Asia has been very recently under water.
We are accustomed to look on Seals as animals which exclusively inhabit salt water; but it is probably from other causes than its saltness that they usually keep to the open sea, and there seems no reason why fresh-water should not suit them quite as well, provided they find in it a sufficiency of food, facilities for rearing their young, and freedom from the attacks of enemies. As already remarked in vol. i. p. 218, Mr. Belt's ingenious hypothesis (founded on personal examination of the Siberian Steppes), that during the Glacial period the northern ice-cap dammed up the waters of the northward flowing Asiatic rivers, and thus formed a vast fresh-water lake which might have risen as high as Lake Baikal, seems to offer the best solution of this curious problem of distribution.
Range of Carnivora in Time.—Carnivora have been found in all the Tertiary deposits, and comprise a number of extinct genera and even families. Several genera of Canidæ occur in the Upper Eocene of Europe; but the most remarkable fact is, that even in the Lower Eocene are found two well-marked forms,Palæonyctis, one of the Viverridæ, andArctocyon, forming a distinct family type of very generalized characters, but unmistakably a carnivore. This last has been found at La Fère, in the north-east of France, in a deposit which, according to M. Gaudry, is the very lowest of the Lower Eocene formation in Europe.Arctocyonis therefore one of the oldest, if not the very oldest, of the higher forms of mammal yet discovered.
Order V.—CETACEA.
Family36.—BALÆNIDÆ. (6 Genera, 14 Species.)
General Distribution.—Temperate and Cold Seas of both Northern and Southern Hemispheres.
This family comprises the whalebone or "right" whales, the best known species being the Greenland whale (Balæna mysticetus). Allied species are found in all parts of the southern seas, as far north as the Cape of Good Hope; while some of the northern species are found off the coast of Spain, and even enter the Mediterranean. As most of the species indicated are imperfectly known, and their classification by no means well settled, no useful purpose will be served by enumerating the genera or sub-genera.
Family37.—BALÆNOPTERIDÆ. (9 Genera, 22 Species.)
General Distribution.—Cold and Temperate Seas of both Hemispheres.
This family comprises the finner whales and rorquals, and are characterised by possessing a dorsal fin and having the baleen or whalebone less developed. They are abundant in all northern seas, less so in the southern hemisphere, but they seem occasionally to enter the tropical seas. The best known genera areMegaptera(7 species);Physalus(4 species); andBalænoptera(2 species); all of which have species in the North Sea.
Family38.—CATODONTIDÆ. (4 Genera, or Sub-Genera, 6 Species.)
General Distribution.—All the Tropical Oceans, extending north and south into Temperate waters.
This family, comprising the cachalots or sperm whales, and black-fish, are separated from the true whales by having teeth in the lower jaw and no whalebone. They are pre-eminently a tropical, as distinguished from the two preceding which arearctic and antarctic families. The spermaceti whale (Catodon macrocephalus) abounds in the Pacific Ocean and in the deep Moluccan Sea, and also in the Indian Ocean and the Mozambique Channel. In the Atlantic it is scarce, although it occasionally comes north as far as our shores.
The genera of Catodontidæ as given by Dr. Gray are,Catodon(2 species?), Warm Eastern Oceans;Physeter(1 species), "the black fish," North Sea;Cogia(2 species), South Temperate Oceans;Euphysetes(1 species), Coast of Australia.
Family39.—HYPEROODONTIDÆ. (9 Genera or Sub-Genera, 12 Species.)
General Distribution.—Atlantic, Mediterranean, Indian Ocean, and Southern Ocean.
This family consists of the beaked whales, which have no permanent teeth in the upper jaw. The genera, according to Dr. Gray, are,Hyperoodon(2 species) "bottle-nosed whales," North Sea;Lagenocetus(1 species), North Sea;Epiodon(2 species), North and South Atlantic;Petrorhynchus(2 species), Mediterranean Sea and Southern Ocean;Berardius(1 species), New Zealand;Xiphius(1 species) North Atlantic;Dolichodon(1 species), Cape of Good Hope;Neoziphius(1 species) Mediterranean;Dioplodon(1 species), Indian Ocean.
Family40.—MONODONTIDÆ. (1 Genus, 1 Species.)
The "Narwhal" (Monodon monoceros) which constitutes this family, is placed by Dr. Gray along with the "white whales," in his family Belugidæ. It inhabits the North Sea.
Family41.—DELPHINIDÆ. (24 Genera or Sub-Genera, 100 Species.)
General Distribution.—All Oceans, Seas, and Great Rivers of the globe.
This family, including the Porpoises, Dolphins, White Whales, &c., may be described as small, fish-shaped whales, having teethin both jaws. According to Dr. Gray they form seven families and 24 genera; according to Professor Carus, four sub-families and 8 genera, but as these groups appear to be established on quite different principles, and often differ widely from each other, I shall simply enumerate Dr. Gray's genera with their distribution as given in his British Museum Catalogue.
Platanista(2 species), long-snouted porpoises, inhabiting the Ganges and Indus;Inia(1 species), a somewhat similar form, inhabiting the upper waters of the Amazonian rivers:Steno(8 species), Indian Ocean, Cape of Good Hope, and West Pacific;Sotalia(1 species), Guiana;Delphinus(10 species), all the oceans;Clymenia(14 species), all the oceans;Delphinapterus(1 species), South Atlantic;Tursio(7 species), Atlantic and Indian Oceans;Eutropia(2 species), Chili, and Cape of Good Hope;Electra, (8 species), all the oceans;Leucopleurus(1 species), North Sea;Lagenorhynchus(1 species), North Sea;Pseudorca(2 species), North Sea, Tasmania;Orcaella(2 species), Ganges;Acanthodelphis(1 species), Brazil;Phocæna(2 species), North Sea;Neomeris(1 species), India;Grampus(3 species), North Sea, Mediterranean, Cape of Good Hope;Globiocephalus(14 species), all the oceans;Sphærocephalus(1 species), North Atlantic;Orca(9 species), Northern and Southern Oceans;Ophysia(1 species), North Pacific;Beluga(6 species), Arctic Seas, Australia;Pontoporia(1 species), Monte Video.
Fossil Cetacea.
Remains of Cetacea are tolerably abundant in Tertiary deposits, both in Europe and North America. In the Lower Pliocene of England, France, and Germany, extinct species of five or six living genera of whales and dolphins have been found; and most of these occur also in the Upper Miocene, along with many others, referred to about a dozen extinct genera.
In the Post-pliocene deposits of Vermont and South Carolina, several extinct species have been found belonging to living genera; but in the Miocene deposits of the Eastern United States cetacean remains are much more abundant, more than 30 species ofextinct whales and dolphins having been described, most of them belonging to extinct genera.
The Zeuglodontidæ, an extinct family of carnivorous whales, with double-fanged serrated molar teeth, whose affinities are somewhat doubtful, are found in the older Pliocene of Europe, and in the Miocene and Eocene of the Eastern United States.Zeuglodonabounds in the United States, and one species reached a length of seventy feet. A species of this genus is said to have been found in Malta.Squalodonoccurs in Europe and North America; and in the latter country four or five other genera have been described, of which one,Saurocetes, has been found also at Buenos Ayres.
Order VI.—SIRENIA.
Family42.—MANATIDÆ. (3 Genera, 5 Species?)
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 ofManatushave been found in the Post-pliocene deposits of Eastern North America fromMaryland to Florida; and an extinct genus,Prorastomus, in some Tertiary deposits in the Island of Jamaica.
In Post-pliocene deposits in Siberia, remains ofRytinahave been found; while several species of the extinct genusHalitherium, perhaps intermediate betweenManatusandHalicore, have been found in the older Pliocene and Upper Miocene of France and Germany.
Order VII.—UNGULATA.
Family43.—EQUIDÆ. (1 Genus, 8 Species.)
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 genusEquusoccurs in Post-pliocene and Pliocene deposits in Europe, North America, and South America. In North America the species are most numerous. An allied genusHipparion, having rudimentary lateral toes, is representedby 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.)
The Tapirs form a small group of animals whose discontinuous distribution plainly indicates their approaching extinction. For a long time only two species were known, the black American, and the white-banded Malay tapir, the former confined to the equatorial forests of South America, the latter to the Malay peninsula, Sumatra, and Borneo (Plate VIII. vol. i. p. 337). Lately however another, or perhaps two distinct species (or according to Dr. J. E. Gray, four!) have been discovered in the Andes of New Granada and Ecuador, at an elevation of from 8,000 to 12,000 feet; while one or perhaps two more, forming the allied genusElasmognathus, have been found to inhabit Central America from Panama to Guatemala.
Extinct Tapirs.—True tapirs inhabited Western Europe, from the latest Pliocene back to the earliest Miocene times; while they only occur in either North or South America in the Post-pliocene deposits and caves. The singular distribution of the living species is thus explained, since we see that they are an Old World group which only entered the American continent at a comparatively recent epoch. An ancestral form of this group—Lophiodon—is found in Miocene and Eocene deposits ofEurope and North America; while a still more ancient form of large size is found in the Lower Eocene of France and England, indicating an immense antiquity for this group of Mammalia. There are many other extinct forms connecting these with the Palæotheridæ, already noticed in chapter vi. (vol. i. pp. 119-125).
Family45.—RHINOCEROTIDÆ. (1 Genus, 9 Species.)
Living Rhinoceroses are especially characteristic of Africa, with Northern and Malayan India. Four or perhaps five species, all two-horned, are found in Africa, where they range over the whole country south of the desert to the Cape of Good Hope. In the Oriental region there are also four or five species, which range from the forests at the foot of the Himalayas eastwards through Assam, Chittagong, and Siam, to Sumatra, Borneo and Java. Three of these are one-horned, the others found in Sumatra, and northwards to Pegu and Chittagong, two-horned. The Asiatic differ from the African species in some dental characters, but they are in other respects so much alike that they are not generally considered to form distinct genera. In his latest catalogue however (1873), Dr. Gray has four genera,Rhinoceros(4 species), andCeratorhinus(2 species), Asiatic;Rhinaster(2 species), andCeratotherium(2 species), African.
Extinct Rhinocerotidæ.—Numerous species ofRhinocerosranged over Europe and Asia from the Post-pliocene back to the Upper Miocene period, and in North America during the Pliocene periodonly. The hornlessAcerotheriumis Miocene only, in both countries. Other genera areLeptodonfrom Greece, andHyracodonfrom Nebraska, both of Miocene age. More than 20 species of extinct rhinoceroses are known, and one has even been found at an altitude of 16,000 feet in Thibet.
Family46.—HIPPOPOTAMIDÆ. (1 Genus, 2 Species.)
The Hippopotamus inhabits all the great rivers of Africa; a distinct species of a smaller size being found on the west coast, and on some of the rivers flowing into Lake Tchad.
Fossil Hippopotami.—Eight extinct species ofHippopotamusare known from Europe and India, the former Post-pliocene or Pliocene, the latter of Upper Miocene age. They ranged as far north as the Thames valley. An extinct genus from the Siwalik Hills,Merycopotamus, according to Dr. Falconer connectsHippopotamuswithAnthracotherium, an extinct form from the Miocene of Europe, allied to the swine.
Family47.—SUIDÆ. (5 Genera, 22 Species.)
The Swine may be divided into three well-marked groups, from peculiarities in their dentition. 1. The Dicotylinæ, orpeccaries (1 genus,Dicotyles). These offer so many structural differences that they are often classed as a separate family. 2. The true swine (3 genera,Sus,Potamochœrus, andBabirusa); and, 3. The Phacochœrinæ, or wart hogs (1 genus,Phacochœrus). These last are also sometimes made into a separate family, but they are hardly so distinct as the Dicotylinæ.
The Peccaries (2 species), are peculiar to the Neotropical region, extending from Mexico to Paraguay. They also spread northwards into Texas, and as far as the Red River of Arkansas, thus just entering the Nearctic region; but with this exception swine are wholly absent from this region, forming an excellent feature by which to differentiate it from the Palæarctic.
Sus(14 species), ranges over the Palæarctic and Oriental regions and into the first Australian sub-region as far as New Guinea; but it is absent from the Ethiopian region, or barely enters it on the north-east.Potamochœrus(3 species?), is wholly Ethiopian (Plate V. vol. i. p. 278).Babirusa(1 species), is confined to two islands, Celebes and Bouru, in the first Australian sub-region.
Phacochœrus(2 species), ranges over tropical Africa from Abyssinia to Caffraria.
Dr. J. E. Gray divides true swine (Sus) into 7 genera, but it seems far better to keep them as one.
Fossil Suidæ.—These are very numerous. Many extinct species of wild hog (Sus), are found in Europe and North India, ranging back from the Post-pliocene to the Upper Miocene formations. In the Miocene of Europe are numerous extinct genera,Bothriodon,Anthracotherium,Palæochœrus,Hyotherium, and some others; while in the Upper Eocene occurCebochœrus,Chœropotamus, andAcotherium,—these early forms having more resemblance to the peccaries.
None of these genera are found in America, where we have the living genusDicotylesin the Post-pliocene and Pliocene deposits, both of North and South America; with a number of extinct genera in the Miocene. The chief of these are,Elotherium,Perchœrus,Leptochœrus, andNanohyus, all from Dakota, andThinohyus, from Oregon. One extinct genus,Platygonus, closely allied toDicotyles, is found in the Post-pliocene of Nebraska,Oregon, and Arkansas.Elotheriumis said to be allied to the peccary and hippopotamus.Hyopotamus, from the Miocene of Dakota, is allied toAnthracotherium, and forms with it (according to Dr. Leidy) a distinct family of ancestral swine.
It thus appears, that the swine were almost equally well represented in North America and Europe, during Miocene and Pliocene times, but by entirely distinct forms; and it is a remarkable fact that these hardy omnivorous animals, should, like the horses, have entirely died out in North America, except a few peccaries which have preserved themselves in the sub-tropical parts and in the southern continent, to which they are comparatively recent emigrants. We can hardly have a more convincing proof of the vast physical changes that have occurred in the North American continent during the Pliocene and Post-pliocene epochs, than the complete extinction of these, along with so many other remarkable types of Mammalia.
According to M. Gaudry, the ancestors of all the swine, with the hippopotami and extinctAnthracotherium,Merycopotamus, and many allied forms,—are theHyracotheriumandPliolophus, both found only in the London clay belonging to the Lower Eocene formation.
Family48.—CAMELIDÆ. (2 Genera, 6 Species).
The Camels are an exceedingly restricted group, the majority of the species now existing only in a state of domestication. The genusCamelus(2 species), is a highly characteristic desert formof 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 anAucheniahas been found, and in those of Kansas one of the extinct genusProcamelus. 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 formHomocamelus. In the Miocene period different genera appear,—Pœbrotherium, andProtomeryx,—while aProcamelushas been found in deposits of this age in Virginia.
In South America a species ofAucheniahas been found in the caves of Brazil, and others in the Pliocene deposits of the pampas, together with two extinct genera,PalæolamaandCamelotherium.
We thus find the ancestors of the Camelidæ in a region where they do not now exist, but which is situated so that the now widely separated living forms could easily have been derived from it. This case offers a remarkable example of the light thrown by palæontology on the distribution of living animals; and it is a warning against the too common practice of assuming the direct land connection of remote continents, in order to explain similar instances of discontinuous distribution to that of the present family.