Family49.—TRAGULIDÆ. (2 Genera, 6 Species.)
The Tragulidæ are a group of small, hornless, deer-like animals, with tusks in the upper jaw, and having some structural affinities with the camels. The musk-deer was formerly classed in this family, which it resembles externally; but a minute examination of its structure by M. Milne-Edwards, has shown it to be more nearly allied to the true deer. The Chevrotains, or mouse-deer,Tragulus(5 species), range over all India to the foot of the Himalayas and Ceylon, and through Assam, Malacca, and Cambodja, to Sumatra, Borneo, and Java (Plate VIII., vol. i. p. 337).Hyomoschus(1 species), is found in West Africa.
Extinct Tragulidæ.—A species ofHyomoschusis said to have been found in the Miocene of the South of France, as well as three extinct genera,Dremotherium(also found in Greece), withLophiomeryxfrom the Upper Miocene, said to be allied toTragulus; andAmphitragulusfrom the Lower Miocene, of more remote affinities, and sometimes placed among the Deer. There seems to be no doubt, however, that this family existed in Europe in Miocene times; and thus another case of discontinuous distribution is satisfactorily accounted for.
Family50.—CERVIDÆ. (8 Genera, 52 Species.)
The Cervidæ, or deer tribe, are an extensive group of animals equally adapted for inhabiting forests or open plains, the Arcticregions or the Tropics. They range in fact over the whole of the great continents of the globe, with the one striking exception of Africa, where they are only found on the shores of the Mediterranean which form part of the Palæarctic region. The following is the distribution of the genera.
Alces(1 species), the elk or moose, ranges all over Northern Europe and Asia, as far south as East Prussia, the Caucasus, and North China; and over Arctic America to Maine on the East, and British Columbia on the west. The American species may however be distinct, although very closely allied to that of Europe.Tarandus(1 species), the reindeer, has a similar range to the last, but keeps farther north in Europe, inhabiting Greenland and Spitzbergen; and in America extends farther south, to New Brunswick and the north shore of Lake Superior. There are several varieties or species of this animal confined to special districts, but they are not yet well determined.Cervus(40 species), the true deer, have been sub-divided into numerous sub-genera characteristic of separate districts. They range over the whole area of the family, except that they do not go beyond 57° N. in America and a little further in Europe and Asia. In South America they extend over Patagonia and even to Tierra del Fuego. They are found in the north of Africa, and over the whole of the Oriental region, and beyond it as far as the Moluccas and Timor, where however they have probably been introduced by man at an early period.Dama(1 species), the fallow deer, is a native of the shores of the Mediterranean, from Spain and Barbary to Syria.Capreolus(2 species), the roe-deer, inhabits all Temperate and South Europe to Syria, with a distinct species in N. China.Cervulus(4 species), the muntjacs, are found in all the forest districts of the Oriental region, from India and Ceylon to China as far north as Ningpo and Formosa, also southward to the Philippines, Borneo, and Java.Moschus(1 species), the musk-deer, inhabits Central Asia from the Amoor and Pekin, to the Himalayas and the Siamese mountains above 8000 ft. elevation. This is usually classed as a distinct family, but M. Milne-Edwards remarks, that it differs in no important points of organisation from the rest of the Cervidæ.Hydropotes(1 species) inhabits China from the Yang-tse Kiang northwards. This new genus has recently been discovered by Mr. Swinhoe, who says its nearest affinities are withMoschus. Other new forms areLophotragus, andElaphodus, both inhabiting North China; the former is hornless, the latter has very small horns about an inch long.
Extinct Deer.—Numerous extinct species of the genusCervusare found fossil in many parts of Europe, and in all formations between the Post-pliocene and the Upper Miocene. The Elk and Reindeer are also found in caves and Post-pliocene deposits, the latter as far south as the South of France. Extinct genera only, occur in the Upper Miocene in various parts of Europe:—Micromeryx,Palæomeryx, andDicrocercushave been described; with others referred doubtfully toMoschus, and an allied genusAmphimoschus.
In N. America, remains of this family are very scarce, aCervusallied to the existing wapiti deer, being found in Post-pliocene deposits, and an extinct genus,Leptomeryx, in the Upper Miocene of Dakota and Oregon. Another extinct genus,Merycodus, from the Pliocene of Oregon, is said to be allied to camels and deer.
In South America, several species ofCervushave been found in the Brazilian caves, and in the Pliocene deposits of La Plata.
It thus appears, that there are not yet sufficient materials for determining the origin and migrations of the Cervidæ. There can be little doubt that they are an Old World group, and a comparatively recent development; and that some time during the Miocene period they passed to North America, and subsequently to the Southern continent. They do not however appear to have developed much in North America, owing perhaps to their finding the country already amply stocked with numerous forms of indigenous Ungulates.
Family51.—CAMELOPARDALIDÆ. (1 Genus, 1 Species.)
The Camelopardalidæ, or giraffes, now consist of but a single species which ranges over all the open country of the Ethiopian region, and is therefore almost absent from West Africa, which is more especially a forest district. During the Middle Tertiary period, however, these animals had a wider range, over Southern Europe and Western India as far as the slopes of the Himalayas.
Extinct Species.—Species ofCamelopardalishave been found in Greece, the Siwalik Hills, and Perim Island at the entrance to the Red Sea; and an extinct genus,Helladotherium, more bulky but not so tall as the giraffe, ranged from the south of France to Greece and North-west India.
Family52.—BOVIDÆ. (34 Genera, 149 Species.)
This large and important family, includes all the animals commonly known as oxen, buffaloes, antelopes, sheep, and goats, which have been classed by many naturalists in at least three, and sometimes four or five, distinct families. Zoologically, theyare briefly and accurately defined as, "hollow-horned ruminants;" and, although they present wide differences in external form, they grade so insensibly into each other, that no satisfactory definition of the smaller family groups can be found. As a whole they are almost confined to the great Old World continent, only a few forms extending along the highlands and prairies of the Nearctic region; while one peculiar type is found in Celebes, an island which is almost intermediate between the Oriental and Australian regions. In each of the Old World regions there are found a characteristic set of types. Antelopes prevail in the Ethiopian region; sheep and goats in the Palæarctic; while the oxen are perhaps best developed in the Oriental region.
Sir Victor Brooke, who has paid special attention to this family, divides them into 13 sub-families, and I here adopt the arrangement of the genera and species which he has been so good as to communicate to me in MSS.
Sub-family I.Bovinæ(6 genera, 13 species). This group is one of the best marked in the family. It comprises the Oxen and Buffaloes with their allies, and has a distribution very nearly the same as that of the entire family. The genera are as follows:Bos(1 sp.), now represented by our domestic cattle, the descendants of theBos primigenius, which ranged over a large part of Central Europe in the time of the Romans. The Chillingham wild cattle are supposed to be the nearest approach to the original species.Bison(2 sp.), one still wild in Poland and the Caucasus; the other in North America, ranging over the prairies west of the Mississippi, and on the eastern slopes of the Rocky Mountains (Plate XIX., vol. ii., p.129).Bibos(3 sp.), the Indian wild cattle, ranging over a large part of the Oriental region, from Southern India to Assam, Burmah, the Malay Peninsula, Borneo, and Java.Poephagus(1 sp.), the yak, confined to the high plains of Western Thibet.Bubalus(5 sp.), the buffaloes, of which three species are African, ranging over all the continental parts of the Ethiopian region; one Northern and Central Indian; and the domesticated animal in South Europe and North Africa.Anoa(1 sp.), the small wild cow of Celebes,a very peculiar form more nearly allied to the buffaloes than to any other type of oxen.
Sub-family II.Tragelaphinæ: (3 genera, 11 species). The Bovine Antelopes are large and handsome animals, mostly Ethiopian, but extending into the adjacent parts of the Palæarctic and Oriental regions. The genera are:Oreas(2 sp.), elands, inhabiting all Tropical and South Africa.Tragelaphus(8 sp.), including the bosch-bok, kudu, and other large antelopes, ranges over all Tropical and South Africa (Plate IV., vol. i., p. 261).Portax(1 sp.) India, but rare in Madras and north of the Ganges.
Sub-family III.Oryginæ: (2 genera, 5 species).Oryx(4 sp.) is a desert genus, ranging over all the African deserts to South Arabia and Syria;Addax(1 sp.) inhabits North Africa, North Arabia, and Syria.
Sub-family IV.Hippotraginæ(1 genus, 3 species). The Sable Antelopes,Hippotragus, form an isolated group inhabiting the open country of Tropical Africa and south to the Cape.
Sub-family V.Gazellinæ(6 genera, 23 species). This is a group of small or moderate-sized animals, most abundant in the deserts on the borders of the Palæarctic, Oriental, and Ethiopian regions.Gazella(17 sp.) is typically a Palæarctic desert group, ranging over the great desert plateaus of North Africa, from Senegal and Abyssinia to Syria, Persia, Beloochistan, and the plains of India, with one outlying species in South Africa.Procapra(2 sp.), Western Thibet and Mongolia to about 110° east longitude.Antilope(1 sp.) inhabits all the plains of India.Æpyceros(1 sp.) the pallah, inhabits the open country of South and South-east Africa.Saiga(1 sp.) a singular sheep-faced antelope, which inhabits the steppes of Eastern Europe and Western Asia from Poland to the Irtish River, south of 55° north latitude. (Plate II., vol. i., p. 218.)Panthalops(1 sp.) confined to the highlands of Western Thibet and perhaps Turkestan.
Sub-family VI.Antilocaprinæ(1 genus, 1 species),Antilocapra, the prong-horned antelope, inhabit both sides of the Rocky Mountains, extending north to the Saskatchewan andColumbia River, west to the coast range of California, and east to the Missouri. Its remarkable deciduous horns seem to indicate a transition to the Cervidæ. (Plate XIX., vol. ii., p.129.)
Sub-family VII.Cervicaprinæ(5 genera, 21 species). This group of Antelopes is wholly confined to the continental portion of the Ethiopian region. The genera are:Cervicapra(4 sp.), Africa, south of the equator and Abyssinia;Kobus(6 sp.), grassy plains and marshes of Tropical Africa;Pelea(1 sp.), South Africa;Nanotragus(9 species), Africa, south of the Sahara;Neotragus(1 sp.) Abyssinia and East Africa.
Sub-family VIII.Cephalophinæ(2 genera, 24 species), Africa and India;Cephalophus(22 sp.), continental Ethiopian region;Tetraceros(2 sp.) hilly part of all India, but rare north of the Ganges.
Sub-family IX.Alcephalinæ(2 genera, 11 species), large African Antelopes, one species just entering the Palæarctic region. The genera are:Alcephalus(9 sp.) all Africa and north-east to Syria;Catoblepas(2 sp.), gnus, Africa, south of the Equator.
Sub-region X.Budorcinæ(1 genus, 2 species)Budorcasinhabits the high Himalayas from Nepal to East Thibet.
Sub-family XI.Rupicaprinæ(1 genus, 2 species) the Chamois,Rupicapra, inhabit the high European Alps from the Pyrenees to the Caucasus. (Plate I., vol. i., p. 195.)
Sub-family XII.Nemorhedinæ(2 genera, 10 species). These goat-like Antelopes inhabit portions of the Palæarctic and Oriental regions, as well as the Rocky Mountains in the Nearctic region.Nemorhedus(9 sp.) ranges from the Eastern Himalayas to N. China and Japan, and south to Formosa, the Malay Peninsula and Sumatra.Aplocerus(1 sp.), the mountain goat of the trappers, inhabits the northern parts of California and the Rocky Mountains.
Sub-family XIII.Caprinæ(2 genera, 23 species). The Goats and Sheep form an extensive series, highly characteristic of the Palæarctic region, but with an outlying species on the Neilgherries in Southern India, and one in the Rocky Mountains and California. The genera areCapra(22 sp.) andOvibos(1 sp.).The genusCapraconsists of several sub-groups which have been named as genera, but it is unnecessary here to do more than divide them into "Goats and Ibexes" on the one hand and "Sheep" on the other—each comprising 11 species. The former range over all the South European Alps from Spain to the Caucasus; to Abyssinia, Persia, and Scinde; over the high Himalayas to E. Thibet and N. China; with an outlying species in the Neilgherries. The latter are only found in the mountains of Corsica, Sardinia, and Crete, in Europe; in Asia Minor, Persia, and in Central and North-Eastern Asia, with one somewhat isolated species in the Atlas mountains; while in America a species is found in the Rocky Mountains and the coast range of California.Ovibos(1 sp.), the musk-sheep, inhabits Arctic America north of lat. 60; but it occurs fossil in Post-glacial gravels on the Yena and Obi in Siberia, in Germany and France along with the Mammoth and with flint implements, and in caves of the Reindeer period; also in the brick earth in the south of England, associated withRhinoceros megarhinusandElephas antiquus.
Extinct Bovidæ.—In the caverns and diluviums of Europe, of the Post-Pliocene period, the remains are found of extinct species ofBos,Bison, andCapra; and in the caverns of the south of FranceRupicapra, and an antelope nearHippotragus.BosandBisonalso occur in Pliocene deposits. In the Miocene of Europe, the only remains are antelopes closely allied to existing species, and these are especially numerous in Greece, where remains referred to two living and four extinct genera have been discovered. In the Miocene of India numerous extinct species ofBos, and two extinct genera,HemibosandAmphibos, have been found, one of them at a great elevation in Thibet. Antelopes, allied to living Indian species, are chiefly found in the Nerbudda deposits.
In North America, the only bovine remains are those of aBison, and a sheep or goat, in the Post-pliocene deposits; and of two species of musk-sheep, sometimes classed in a distinct genusBootherium, from beds of the same age in Arkansas and Ohio.Casoryx, from the Pliocene of Nebraska, is supposed to be allied to the antelopes and to deer.
In the caves of Brazil remains of two animals said to be antelopes, have been discovered. They are classed by Gervais in the generaAntilopeandLeptotherium, but the presence of true antelopes in S. America at this period is so improbable, that there is probably some error of identification.
The extinct family Sivatheridæ, containing the extraordinary and gigantic four-hornedSivatheriumandBramatherium, of the Siwalik deposits, are most nearly allied to the antelopes.
From the preceding facts we may conclude, that the great existing development of the Bovidæ is comparatively recent. The type may have originated early in the Miocene period, the oxen being at first most tropical, while the antelopes inhabited the desert zone a little further north. The sheep and goats seem to be the most recent development of the bovine type, which was probably long confined to the Eastern Hemisphere.
General Remarks on the Distribution of the Ungulata.
With the exception of the Australian region, from which this order of mammalia is almost entirely wanting, the Ungulata are almost universally distributed over the continental parts of all the other regions. Of the ten families, 7 are Ethiopian, 6 Oriental, 5 Palæarctic, 4 Neotropical, and 3 Nearctic. The Ethiopian region owes its superiority to the exclusive possession of the hippopotamus and giraffe, both of which inhabited the Palæarctic and Oriental regions in Miocene times. The excessive poverty of the Nearctic region in this order is remarkable; the swine being represented only byDicotylesin its extreme southern portion, while the Bovidæ are restricted to four isolated species. Deer alone are fairly well represented. But, during the Eocene and Miocene periods, North America was wonderfully rich in varied forms of Ungulates, of which there were at least 8 or 9 families; while we have reason to believe that during the same periods the Ethiopian region was excessively poor, and that it probably received the ancestors of all its existing families from Europe or Western Asia in later Miocene or Pliocene times. Many types that once abounded in both Europe and North America are now preserved only in South America and Central or Tropical Asia,—asthe tapirs and camels; while others once confined to Europe and Asia have found a refuge in Africa,—as the hippopotamus and giraffe; so that in no other order do we find such striking examples of those radical changes in the distribution of the higher animals which were effected during the latter part of the Tertiary period. The present distribution of this order is, in fact, utterly unintelligible without reference to the numerous extinct forms of existing and allied families; but as this subject has been sufficiently discussed in the Second Part of this work (Chapters VI. and VII.) it is unnecessary to give further details here.
Order VIII.—PROBOSCIDEA.
Family53.—ELEPHANTIDÆ. (1 Genus, 2 Species.)
The elephants are now represented by two species, the African, which ranges all over that continent south of the Sahara, and the Indian, which is found over all the wooded parts of the Oriental region, from the slopes of the Himalayas to Ceylon, and eastward, to the frontiers of China and to Sumatra and Borneo. These, however, are but the feeble remnants of a host of gigantic creatures, which roamed over all the great continents except Australia during the Tertiary period, and several of which were contemporary with man.
Extinct Elephants.—At least 14 extinct species ofElephas, and a rather greater number of the allied genusMastodon(distinguished by their less complex grinding teeth) have now beendiscovered. Elephants ranged over all the Palæarctic and Nearctic regions in Post-Pliocene times; in Europe and Central India they go back to the Pliocene; and only in India to the Upper Miocene period; the number of species increasing as we go back to the older formations.
In North America two or three species ofMastodonare Post-pliocene and Pliocene; and a species is found in the caves of Brazil, and in the Pliocene deposits of the pampas of La Plata, of the Bolivian Andes, and of Honduras and the Bahamas. In Europe the genus is Upper Miocene and Pliocene, but is especially abundant in the former period. In the East, it extends from Perim island to Burmah and over all India, and is mostly Miocene, but with perhaps one species Pliocene in Central India.
An account of the range of such animals as belong to extinct families of Proboscidea, will be found in Chapters VI. and VII.; from which it will be seen that, although the family Elephantidæ undoubtedly originated in the Eastern Hemisphere, it is not improbable that the first traces of the order Proboscidea are to be found in N. America.
Order IX.—HYRACOIDEA.
Family54.—HYRACIDÆ. (1 Genus. 10-12 Species.)
The genusHyrax, which alone constitutes this family, consists of small animals having the appearance of hares or marmots, but which more resemble the genusRhinocerosin their teeth and skeleton. They range all over the Ethiopian region, except Madagascar; a peculiar species is found in Fernando Po, and they just enter the Palæarctic as far as Syria. They may therefore be considered as an exclusively Ethiopian group. In Dr. Gray'slast Catalogue (1873) he divides the genus into three—Hyrax,EuhyraxandDendrohyrax—the latter consisting of two species confined apparently to West and South Africa.
No extinct forms of this family have yet been discovered; theHyracotheriumof the London clay (Lower Eocene) which was supposed to resembleHyrax, is now believed to be an ancestral type of the Suidæ or swine.
Order X.—RODENTIA.
Family55.—MURIDÆ. (37 Genera, 330 Species.)
The Muridæ, comprising the rats and mice with their allies, are almost universally distributed over the globe (even not reckoning the domestic species which have been introduced almost everywhere by man), the exceptions being the three insular groups belonging to the Australian region, from none of which have any species yet been obtained. Before enumerating the genera it will be as well to say a few words on the peculiarities of distribution they present. The true mice, forming the genusMus, is distributed over the whole of the world except N. and S. America where not a single indigenous species occurs, being replaced by the genusHesperomys; five other genera, comprehending all the remaining species found in South America are peculiar to the Neotropical region. Three genera are confined to the Palæarctic region, and three others to the Nearctic. No less than twelve genera are exclusively Ethiopian, while only three are exclusively Oriental and three Australian.
Mus(100-120 sp.) the Eastern Hemisphere, but absent from the Pacific and Austro-Malayan Islands, except Celebes and Papua;Lasiomys(1 sp.) Guinea;Acanthomys(5-6 sp.) Africa, India andN. Australia;Cricetomys(1 sp.) Tropical Africa;Saccostomus(2 sp.) Mozambique;Cricetus(9 sp.) Palæarctic region and Egypt;Cricetulus(1 sp., Milne-Edwards, 1870) Pekin;Pseudomys(1 sp.) Australia;Hapalotis(13 sp.) Australia;Phlæomys(1 sp.) Philippines;Platacanthomys(1 sp., Blyth, 1865) Malabar;Dendromys(2 sp.) S. Africa;Nesomys(1 sp. Peters, 1870) Madagascar;Steatomys(2 sp.) N. and S. Africa;Pelomys(1 sp.) Mozambique;Reithrodon(9 sp.) N. America, Lat. 29° to Mexico, and south to Tierra del Fuego;Acodon(1 sp.) Peru;Myxomys(1 sp.) Guatemala;Hesperomys(90 sp.) North and South America;Holochilus(4 sp.) South America;Oxymycterus(4 sp.) Brazil and La Plata;Neotoma(6 sp.) U.S., East coast to California;Sigmodon(2 sp.) Southern United States;Drymomys(1 sp.) Peru;Neotomys(2 sp.) S. America;Otomys(6 sp.) S. and E. Africa;Meriones=Gerbillus(20-30 sp.) Egypt, Central Asia, India, Africa;Rhombomys(6 sp.) S. E. Europe, N. Africa, Central Asia;Malacothrix(2 sp.) South Africa;Mystromys(1 sp.) South Africa;Psammomys(1 sp.) Egypt;Spalacomys(1 sp.) India;Sminthus(1-3 sp.) East Europe, Tartary, Siberia;Hydromys(5 sp.) Australia and Tasmania;Hypogeomys(1 sp., Grandidier, 1870) Madagascar;Brachytarsomys(1 sp., Günther, 1874) Madagascar;Fiber(2 sp.) N. America to Mexico;Arvicola(50 sp.) Europe to Asia Minor, North Asia, Himalayas, Temp. N. America;Cuniculus(1 sp.) N. E. Europe, Siberia, Greenland, Arctic America;Myodes(4 sp.) Europe, Siberia, Arctic America, and Northern United States;Myospalax=Siphneus(2 sp.) Altai Mountains and N. China[4];Lophiomys(1 sp.) S. Arabia, and N. E. Africa;Echiothrix(1 sp.) Australia.
Extinct Muridæ.—Species ofMus,Cricetus,Arvicola, andMyodes, occur in the Post-Pliocene deposits of Europe;Arvicola,Meriones, and the extinct genusCricetodon, with some others, in the Miocene.
In North America,Fiber,Arvicola, andNeotoma, occur in caves;an extinct genus,Eumys, in the Upper Miocene of Dakota, and another,Mysops, in the Eocene of Wyoming.
In South AmericaMus, or more probablyHesperomys, is abundant in Brazilian caverns, andOxymycterusin the Pliocene of La Plata; whileArvicolais said to have occurred both in the Pliocene and Eocene deposits of the same country.
Family56.—SPALACIDÆ. (7 Genera, 17 Species.)
The Spalacidæ, or mole-rats, have a straggling distribution over the Old World continents. They are found over nearly the whole of Africa, but only in the South-east of Europe, and West of Temperate Asia, but appearing again in North India, Malacca, and South China.Ellobius(1 sp.), is found in South Russia and South-west Siberia;Spalax(1 sp.), Southern Russia, West Asia, Hungary, Moldavia, and Greece (Plate II., vol. i. p. 218);Rhizomys(6 sp.), Abyssinia, North India, Malacca, South China;Heterocephalus(1 sp.), Abyssinia;Bathyerges(=Orycterus1 sp.), South Africa;Georychus(6 sp.), South, Central, and East Africa;Heliophobus(1 sp.), Mozambique.
Family57.—DIPODIDÆ. (3 Genera, 22 Species.)
The Jerboas, or jumping mice, are especially characteristic of the regions about the eastern extremity of the Mediterranean, being found in South Russia, the Caspian district, Arabia, Egypt,and Abyssinia; but they also extend over a large part of Africa, and eastward to India; while isolated forms occur in North America, and the Cape of Good Hope.Dipus=Gerbillus(20 sp.), inhabits North and Central Africa, South-East Europe, and across Temperate Asia to North China, also Afghanistan, India, and Ceylon;Pedetes(1 sp.), South Africa to Mozambique and Angola;Jaculus=Meriones(1 sp.), North America, from Nova Scotia and Canada, south to Pennsylvania and west to California and British Columbia (Plate XX., vol. ii. p.135).
Extinct Dipodidæ.—Dipusoccurs fossil in the Miocene of the Alps; and an extinct genus,Issiodromys, said to be allied toPedetesof the Cape of Good Hope, is from the Pliocene formations of Auvergne in France.
Family58.—MYOXIDÆ. (1 Genus, 12 Species.)
The Dormice (Myoxus), are small rodents found over all the temperate parts of the Palæarctic region, from Britain to Japan; and also over most parts of Africa to the Cape, but wanting in India. Some of the African species have been separated under the name ofGraphidurus, while those of Europe and Asia form the sub-generaGlis,Muscardinus, andEliomys.
Extinct Myoxidæ.—Myoxusranges from the Post-pliocene of the Maltese caverns to the Miocene of Switzerland and the Upper Eocene of France; and an extinct genusBrachymysis found in the Miocene of Central Europe.
Family59.—SACCOMYIDÆ. (6 Genera, 33 Species.)
The Saccomyidæ, or pouched rats, are almost wholly confined to our second Nearctic sub-region, comprising the Rocky Mountains and the elevated plains of Central North America. A few species range from this district as far as Hudson's Bay on the north, to South Carolina on the east, and to California on the west, while one genus, doubtfully placed here, goes south as far as Honduras and Trinidad. The group must therefore be considered to be pre-eminently characteristic of the Nearctic region.
The genera are,—Dipodomys(5 sp.), North Mexico, California, the east slope of the Rocky Mountains to the Columbia River, and one species in South Carolina;Perognathus(6 sp.), North Mexico, California, east slope of the Rocky Mountains to British Columbia;Thomomys(2 sp.), Upper Missouri, and Upper Columbia Rivers to Hudson's Bay;Geomys(5 sp.), North Mexico, and east slope of Rocky Mountains to Nebraska (Plate XIX., vol. ii. p.129);Saccomys(1 sp.), North America, locality unknown;Heteromys(6 sp.), Mexico, Honduras, and Trinidad.GeomysandThomomysconstitute a separate family Geomyidæ, of Professor Carus; but I follow Professor Lilljeborg, who has made a special study of the Order, in keeping them with this family.
In the Post-Pliocene deposits of Illinois and Nebraska, remains of an existing species ofGeomyshave been found.
Family60.—CASTORIDÆ. (1 Genus, 2 Species.)
The Beavers, forming the genusCastor, consist of two species, the American (Castor canadensis) ranging over the whole of North America from Labrador to North Mexico; while the European (Castor fiber) appears to be confined to the temperate regions of Europe and Asia, from France to the River Amoor, over which extensive region it doubtless roamed in prehistoric times, although now becoming rare in many districts.
Extinct Castoridæ.—Extinct species ofCastorrange back from the Post-pliocene to the Upper Miocene in Europe, and to the Newer Pliocene in North America. Extinct genera in Europe are,Trogontherium, Post-Pliocene and Pliocene;Chalicomys, Older Pliocene; andSteneofiber, Upper Miocene. In North AmericaCastoroidesis Post-Pliocene, andPalæocastor, Upper Miocene. The family thus first appears on the same geological horizon in both Europe and North America.
Family61.—SCIURIDÆ.—(8 Genera, 180-200 Species.)
The Squirrel family, comprehending also the marmots and prairie-dogs, are very widely spread over the earth. They are especially abundant in the Nearctic, Palæarctic, and Oriental regions, and rather less frequent in the Ethiopian and Neotropical, in which last region they do not extend south of Paraguay. They are absent from the West Indian islands, Madagascar, and Australia, only occurring in Celebes which doubtfully belongs to the Australian region. The genera are as follows:—