Page images
PDF
EPUB

shared by the contiguous region to the southward. For the present I prefer to still retain it as a division of the first rank. It is character. ized mainly by the paucity of its life, as compared with every region except the Antarctic, and by what it has not rather tban by the possession of pecaliar species or groups. It wholly lacks both Amphibian and Reptilian life, is almost exclusively the summer home of many birds, and forms the habitat of the Esquimaus, the Arctic Fox, the Polar Bear, the Musk Ox, the Polar Hare, the Lemmings, the Walruses, the Narwhal, and the White Whale, which are confined within it. It has no Chiroptera nor Insectivora, two or three species of Shrews, however, barely reacbing its southern border. It shares with the cold-temperate belt the presence of the Moose and the Reindeer, several Pinnipeds, a number of boreal species of Glires, several fur-bearing Carnivora, and a considerable number of birds. Its southern boundary may be considered as coinciding very nearly with the northern limit of arboreal vegetation, and hence approximately with the isotherm of 320 F. Its more characteristic terrestrial forms range throughout its extent, none being restricted to eitber the North American or Europæo-Asiatic continent. Hence it is indivisible into regions of the second and third grades (regions and provinces), and may be considered as embracing a single hyperborean assemblage of life.

II.—NORTH-TEMPERATE REALM. Very few writers on zoölogical geography have failed to recognize the striking resemblance the fauna of Temperate North America bears to that of the corresponding portion of the Old World. The resem. blance is less in the Avian class than among mammals, but is generally acknowledged as obtaining even there. Dr. Sclater, while admitting a strong resemblance between these areas, considered them as separable into two primary regions, in which view of the case he has been followed, among prominent writers on the subject, by Dr. Günther, Mr. Wallace, Mr. Murray, and Professor Ccpe. Dr. Günther, while provisionally accepting Dr. Sclater's “ Nearctic” and “ Palæarctic” regions, refers pointedly to the disagreement of the distribution of Batrachians with these divisions; for in discussing the distribution of this class he says," Dissimilarity and similarity of the Batracho-fauna depend upon zones. Palæarctic and Nearctic regions resemble each otber more than any other third; the same is the case with Australia and South America; the Ethiopian region exhibits similarity with South America, as well as with the East Indies, but more especially with the latter.'* Mr. Murray admits that “the boreal extremity of North America is tinged with a Europeo Asiatic admixture”, which he regards as “an extraneous element grafted upon the genuine stock, and easily eliminated from it”. But in his map of " Great Mammalian Regions” the boreal parts of

* Proc. Zool. Soc. Lond., 1858, p. 390.
Geogr. Dist. Mam., p. 312.

both continents are similarly colored, the same color, however, extending only to about the forty.ninth degree of north latitude in North America, while in Africa it descends to north latitudo 180, aud in Asia ranges from north latitude 300 to 250! His divisions as recognized in the text are still more arbitrary and unphilosophic.

Mr. Wallace, in his discussion of zoological regions, says, " The dis. tinction between the characteristic forms of life in tropical and cold countries is, on the whole, very strongly marked in the northern bemi. sphere; and to refuse to recognize this in a subdivision of the earth which is established for the very purpose of expressing such contrasts more clearly and concisely than by ordinary geographical terminology, would be both illogical and inconvenient. The one question then remains, whether the Nearctic region should be kept separate or whether it should form part of the Palearctic or of the Neotropical. Professor Huxley and Mr. Blyth advocate the former course; Mr. Andrew Murray (for mammalia) and Professor Newton (for birds) think the latter woull be more natural. No doubt,” Mr. Wallace adds, "much is to be said for both views," but decides in favor of the separation of the two regions in accordance with Dr. Sclater's scheme.*

While Mr. Blyth includes North America in his “Boreal Region" (as 66 2. Neo-septentrional Sub-region”), he adds also Central America and the Antilles (as “3. Neo-meridional Sub-region"), and, still more strangely, the Andean Region, with Chili, Patagonia, and the Fuegian and Falkland Archipelagos (as “4. Andesian Sub-region”).t

Professor Huxley, in writing of the primary ontological regions of the globe, thus observes:-"In a well known and very valuable essay on the Geographical Distribution of Birds, Dr. Sclater divides the surface of the globe primarily into an eastern and a western area, which be terms respectively Palxogea and Neogwa. However, if we take into consideration not merely the minor differences on which the species and genera of birds and mammals are often based, but weigh the morphological value of groups, I think it becomes clear that the Nearctic province is really far more closely allied with the Palæarctic than with the Neotropical region, and that the inhabitants of the Indian and Ethiopian regions are much more nearly connected with one another and with those of the Palæarctic region than they are with those of Australia. And if the frontier line is latitudinal rather than longitudinal, and di. vides a north world from a south world, we must speak of Arctogaa and Notogæa rather than of Neogæa and Palæogæa as the primary distributional areæ. The secondary divisions, or geographical provinces, proposed by Dr. Sclater, answer, in great measure, to those which are suggested by the distribution of the Alectoromorphar-except that, in common with many other naturalists, I think it would be convenient to recognize a circumpolar province, as distinct from the Nearctic and

*Geogr. Dist. Anim., vol. I, pp. 65, 66.
† Nature, vol. iii, p. 427, March 30, 1871.

Palæarctic regions."* Professor Huxley thus emphatically recognizes a region equivalent to my North Temperate Realm.

Mr. Robert Brown, in writing of the distribution of the mammals of Greenland, also recognizes a North Temperate Region, wbich he divides into a European Temperate Province and a North American Temperate Province, from which he separates a Circumpolar Region, equivalent to the Arctic Realm above characterized.t

Dr. Gill, in regard to fishes, recognizes an "Arctogæan” region, "em. bracing Europe, Northern Asia, and Northern America”, as distinct on the one hand from the American Tropical and Transtropical Region, and on the other from Tropical Asia and Africa. I

Dr. Packard, in discussing the distribution of the Phalænid Motus, recognizes both an Arctic Realm and a North Temperate Realm, as here characterized. Referring to a previously given table of subalpine and circumpolar species, he says, "This table indicates how wide are the limits of distribution of these species, and it will be seen how important it is to follow circumpolar and north-temperate insect-faunæ around the globe, from continent to continent. It will be then seen how inadequate must be our views regarding the geographical distribution of the animals and plants of our own continent, without specimens from similar regions in the same zones in the Old World. It will be found that for the study of the insect-fauna of the Rocky Mountains and Pacific coast we must have ample collections from the Ural and Altai Mountains and surrounding plateaus,” etc.

Dr. August von Pelzeln also recognized a circumboreal region (ark. tische Region"), and considers the “ Nearctic” and “Palæarctic” as form. ing inseparable parts of a single region. He says:-"Die paläarktische Region scheint mir von der nearktischen nicht trennbar zu sein, son. dern beide dürften ein Ganzes bilden, welches man als arktische Region bezeichnen könnte. Ihre Zusammengehörigkeit tritt mit voller Evidenz in den hoch nordischen Ländern des alten und neuen Continentes hervor und erst in niedereren Breiten macht sich die Differenzirung geltend.

* Proc. Zool. Soc. Lond., 1868, pp. 314,315. + Proc. Zool. Soc. Lond., 1868, pp. 337, 338.

# Says Dr. Gill :-“In fine, dividing the earth into regions distinguished by general ichthyological peculiarities, several primary combinations may be recognized, viz. :-1, an Arctogwan, embracing Europe, Northern Asia, and Northern America ; 2, an Asiatic, embracing the tropical portions of the continent; 3, African, limited to the region south and east of the Desert; 4, an American (embracing the America par excellence dedicated to Amerigo Vespucci), including the tropical and transtropical portions; and, 5, an Australasian. Further, of these (a) the first two [Arctogæan and Asiatic] have intimate relations to each other, and (b) the last three others among themselves; and some weighty arguments may be adduced to support a division of the faunas of the globe into two primary regions coinciding with the two combinations alluded to-(a) a nogma and (b) an Eogæa, which might represent areas of derivation or gain from more or less distant geological epochs.”- Ann. and Mag. Nat. Hist., 4th ser., vol. xv, 1875, pp. 254, 255.

V Monograph of Geometrid Moths, or Phalænidæ, of the United States, pp. 567, 586, 1876.

[ocr errors]

Die Vergleichung der Thierwelt beider Continente zeigt dämlich, dass die circumpolare Fauna in beiden dieselbe ist, dass in der Hochgebirgsfauna noch bedeutende Uebereinstimmung herrscht, dass in der übrigen paläo- und neoborealen Thierbevölkerung sowohl identische Arten als gemeinsam eigenthümliche Gattungen sich finden, endlich dass selbst jene Typen, welche jedem Continente eigenthümlich sind, doch eine ge. wisse Uebereinstimmung hinsichtlich des Charakters der Fauna an sich tragen, so dass sie einander näher stehen als Angehörigen anderer Regionen. In der neuen Welt ist eine Modification der Fauna auch durch das Eindringen neotropischer Formen gegeben."* He further also calls attention to the similarity of life which prevailed throughout this cir: cumpolar region during the Quaternary period.

It is unnecessary to cite further, from the abundant material at land, the opinions of specialists in reference to the propriety of recognizing a North Temperate Realm, as distinguished from the tropical regions of the globe, and in contradistinction from a north and south line of divi. sion of the North Temperate Zone into two primary (“Palæarctic" and 6 Nearctic") regions.

The chief differences between Dr, Sclater's division of the northern hemisphere and the present consist in setting off at the northward an Arctic Realm, the union of the so-called Nearctic and Palæarctic Regions into one circumpolar belt, and in the adoption for the same of a more northern limit than that proposed as the boundary of the two abovenamed Sclaterian regions. As will be shown later, the subdivisions of the North Temperate Realm or (“Arctogæa") as here defined agree in the main with the “subregions” of Sclater and Wallace. The more northward location of the southern boundary of the North Temperate Realın in North America results in the elimination of several character. istic tropical types, which extend a short way only into Dr. Selater's Nearctic and Palæarctic Regions, and which, when considered as members of these regions, give false or misleading results when the two regions are contrasted on a numerical basis, grounded on the proportion of peculiar types,-numerous forms being thus reckoned as components of the Nearctic and Palæarctic regions wbich are properly tropical.

In North America, the division between characteristic temperate and tropical forms of life approximately coincides with the isotherm of 680

F., or somewhere between 680 and 700 F. This line begins on the At*lantic coast a little below the northern boundary of Florida, and runs thence westward along the Gulf coast to Southern Texas, and thence farther westward to the Pacific, not far from the international bound. ary between the United States and Mexico, swerving more or less northward or southward in accordance with the configuration and elevation of the land-surface. It thus leaves the greater part of the peninsula of Florida within the American Tropical Realm, to wbich the fauna of its southern half is certainly closely allied. A portion of the Mexican high. lands are undoubtedly to be included in the North Temperate Realm, but their fauna is too little known to admit of the boundary being at present definitely drawn.

* Verbandl. der K. K. Zool.- Bot. Gesell. in Wien, Bu. xxv, 1876, pp. 50, 51; see also p. 62.

On the other hand, the lower portion of the Great Colorado Valley and the coast region of Southern California are, perhaps, better referable to the American Tropical Realm than to the North Temperate. At the junction of the two realms, 'there must be a belt of debatable or doubtful ground. The approximate boundary I would place near the northern limit ofdistribution of such mammalian forms as Nasua, Dicotyles, Manatus, Dasypus, and the tropical species of Felis (as, F. onca, F. par. dalis, F. eyra, and F. yaguarundi). This boundary also coincides quite nearly with the southern limit of distribution of the Lynxes, the Gray and Prairie Wolves, the Common Fox, the Mink, the Black and Grizzly Bears, the Wapati and Virginian Deer, the Bison, the Pronghorn, the Beaver, Prairie Dogs, Muskrat, the Arvicolæ, and the Moles (Scalops and Condylura). Bassaris is properly tropical, although straggling cousiderably far. ther northward than the other above-mentioned forms. Florida, for convenience, might be allowed to stand as a portion of the North Temperate Realm, although, as I have previously shown, it forms a distinct fauna, with strongly tropical affinities,* it having not less than twelve characteristically tropical genera of birds, several tropical genera of mammals (notably the Manatee and several Bats), and also several tropical genera of Reptiles and Batrachians, none of which range much, if any, to the northward of its southern balf.

The southern boundary of the North Temperate Realm in the Old World may be doubtless approximately drawn near the same isotherm (about the mean annuals of 680 to 700 F.). This coincides closely with the southern boundary of the so-called Palæarctic Region. There is, however, here a broader belt of debatable or transitional ground than in the New World, into wbich so many tropical forms extend that it becomes almost a question whether the boundary between Tropical and Temperate life should not be carried considerably more to the northward, so as to leave Mr. Wallace's “sub-regions" 2 and 4 (Mediterranean and Manchurian) in the Tropical Realm rather than in the North Temperate. Despite, however, the presence of a considerable number of tropical genera in these regions, the North Temperate forms still greatly predominate. In the Western or “Mediterranean" district, for instance, we have species of Macacus, one of which even reaches the Spanish Penin. sula. Herpestes has a similar northward extension. Hyæna and Hystrix range not only over most of this district, but also over the greater part of the Manchurian, where we again find a species of Macacus, and meet with Semnopithecus, wbile Hyrax just enters the Mediterranean from the southward. On the western border of the Manchurian we get also Pteropine Bats, and species of Equidae, straggling remnants of the more

* Bull. Mus. Zool., vol. ii, pp. 391, 392.

« EelmineJätka »