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northward extension of tropical life which inhabited this region during the middle and later portions of the Tertiary Period and in the Quaternary.

Divisions of the North Temperate Realm.- The North Temperate Realm is primarily divisible in two directions, giving in each two regions, namely, (1) by a longitudinal division into (a) a North American Region and (b) a Europcro-Asiatic Region; and (2) latitudinally, into (a) a Cold Temperate and (b) a Warm Temperate Region. The Cold Temperate, if limited on both continents by the isotherm of 360 F., presents a nearly uniform fauna throughout, its southern limit in botlı corresponding with the natural (that is, before modified by human agency) southern limit of distribution of Tarandus and Alces. While there is at this point in North America a well-marked transition in the fauna, the change in Europe and Asia appears to be less marked, the first important transition in the Old World being much farther southward, even as low almost as the isotherm of 600 F. Hence the divisions of the Temperate Realm in the Old World partake of the nature of temperate and subtropical rather than cold-temperate and warm-temperate. Here, in consequence of the great elevation and extent of the Himalayan Plateau, the northern or temperate division is greatly narrowed in Central Asia, where it becomes, according to Mr. Wallace, almost wholly separated into two quite widely detached regions, namely, the " Mediterranean” and “ Manchurian Subregions”.

As thus divided, the temperate and subtropical divisions of the Old World are very strongly marked. The latter consists mainly of Northern Africa, Asia Minor, Persia, Afgbanistan and Beloochistan, Northern China, and Manchuria, with barely a parrow belt along the Mediterranean coast of Europe and the Spanish Peninsula. As already stated, it is strongly tinged with tropical forms. While there is a general prevalence of temperate types, we meet also with the large and essentially tropical forms of Felis, several Monkeys, several species of Viverridæ, Hyæna, Hystrix, Equus, and other distinctively tropical or subtropical types. The northern or temperate division of the EuropæoAsiatic Region seems to constitute two well-marked provinces, the one Eastern or European, the other Western or Asiatic. The former corresponds with Mr. Wallace's “ European Subregion", exclusive of its northern third ; the latter with his “ Siberian Subregion", exclusive likewise of its boreal portion. For the southern or subtropical division I adopt the subdivisions proposed by Mr. Wallace, witb, for the present, the boundaries he has assigned them,-namely, a Western or Mediterranean Province and an Eastern or Manchurian Province. These two provinces, as already noted, are quite widely separated, in consequence of the southward extension of the cold-temperate fauna over the Thibetan plateau to the Himalayas. The fauna of the Thibetan plateau is said by Mr. Blandford to be “essentially Boreal, Alpine and even Arctic types prevailing, the country having in many parts a cli. mate scarcely equalled elsewhere for intensity of cold out of the Arctic Regions. This high barren tableland extends from Afghanistan to Yunau; it comprises the drainage-areas of the Upper Indus and the Sanpú, and is bounded on the north in its western portion by the Kuenluen range, but it is less defined and its boundaries less accurately known to the eastwaru, although much light has beeu thrown upon the subject by Prejewalski's explorations”* In the “ List of Mammalia known to inbabit the Thibetan Plateau”, given by Mr. Blandford, the only distinct. ively southern genus is Equus. The only peculiar genus is Poëphagus, but the list is evidently quite incomplete, the only Bat given being a species of Plecotus, and the only Insectivore a species of "Crocidura. Budorcas, usually attributed to Tbibet, is excluded, and several other genera, as Nectogale, Uropsilus, and Æluropus, currently given as peculiar to the Thibet plateau, are not mentioned. While the Thibetan plains belong certainly to the colder division, so many types mainly restricted to this region occur that the question arises whether it may not be proper to recognize the region as a Thibetian Province of the Temperate Subregion.

North American Region. The North American Region has been divided by Professor Baird into three "provinces", termed respectively “ Eastern”, “ Middle”, and “Western". Though not co-ordinate in point of differentiation with the divisions of the Europæo-Asiatic Region above recogaized as provinces, they nevertheless possess distinctive features and form natural regions. They are of course far smaller in area, and possess a much smaller number of genera, but have about the same proportion of peculiar generic and subgeneric types.

In the subjoined tables an attempt is made to give lists of the genera of the two primary divisions of the North Temperate Realm, with approximate indications of their distribution in the various subdivisions of the two regions.f

* Proc. Zool. Soc. Lond., 1876, pp. 632, 633.

+ In these lists, as elsewhere in the tabulated lists given in this paper, it is not assumed tbat the groups adopted as "genera” are always of co-ordinate value. The equation attempted is doubtless open in many cases to criticism. While the attempt is made to assume an intermediate position between undue conservatism and excessive multiplication in respect to groups assumed by different writers as “geveric”, the lists can of course be considered only as provisional. Again, it is occasionally difficult to decide whether certain genera should be assigued, even in a general way, to one of the faunal divisions rather than to another. However defective the result, the intent has of course been to give a fair presentation of the facts of distribution,

Genera of the North American Region.
NOTE.—The names of circumpolar genera are in italics ; those of genera peculiar to the region, la

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Lynx ...........
Canis ............
Vulpes ...........
UROCYON ..........
Gulo .....
Mustela ...
Putorius ...
MEPHITIS ...
SPILOGALE ........
TAXIDEA....
Iritra......
Enhydris ........
Procyon .........
Ursus ............
Phoca ..........
Pagomys .....
Pagophilus .........
Erignathus.........
Halichærus .........
Cystophora.........
Eumetopias.......
Zalopbus ..........
Callorhinus .......
Alces............
Rangifer ........
Cerrus...
CARIACUS .......
MAZAMA ..........
Ovis ...........
Bison .............
ANTILOCAPRA.
Nyctinomus........
Nycticejus .........
Lasiurus...........
Vesperugo..........
Vespertilio ........
Symotus...........
Antrozous..
SCALOPS
SCAPANUS....
Urotrichus....
NEOSOHEX ........
Sorex ...........
BLARINA ..........
Sciuropterus .......

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Tamias ..........
Spermophilus .....
CYNOMYS..........
Arctomys .........
HAPLODON ........
Neotoma..........
Sigmodon .........
OCHETODON.......
Hesperomys ......
Arvicola
Evotomys. ........
SYXAPTOMY8 ......
FIBER......
ZAPUS....
PEROGNATHUS....
CRICETODIPL'S ....
DIPODOXYS.......
GEOMYS......
THOMOMYS........
Castor ............
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Lepus.....
Lagomys ..........
Didelphys .......

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Summary.
Whole number of genera ........
Peculiar to the region ......
Circumpolar ....
Of general distribution throughout the region....
Occurring in the Cold Temperate Subregion.....
Occurring in the Warm Temperate Subregion.....
Land genera represented in the Eastern Province...
Genera represented in the Middle Province.
Land genera represented in the Western Province ...........
Land genera restricted to the Eastern Province..
Genera common to the Middle and Western Provinces not represented in

Eastern Province................
Genera restricted to the Middle Province.....
Land genera restricted to the Western Province....
Maritime genera restricted to the Eastern Province ....
Maritime genera restricted to the Western Province .......
Maritime genera occurring in both Eastern and Western Provinces .......

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Europão-Asiatic Region.—The Europæo-Asiatic Region embraces a far greater (about four times greater) area than the North American, and is physically much more highly diversified. It is similarly divisible into a Cold Temperate Subregion and a Warm Temperate Subregion, and is further differentiated into a number of well-marked provinces, two of which belong to the Cold Temperate Subregion, and three or more to the Warm Temperate Subregion.*

Genera of the Europæo-Asiatic Region. (Note.-A few almost exclusively tropical genera, which barely reach or doubtfully extend a short distance over the southern boundary of the region, are omitted as being not properly faunal elements of the region.

The names of circumpolar gepera are in italics ; those of genera peculiar to the region in SMALL CAPE

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Felis ....
Lynx ...........
Cynælurus..........
Genctta.....
Herpestes...........
Hyæna .............
Canis ....
Cuon...........
Vu'pes ..............
Arctonyx ...........
NYCTEREUTES ....
Gulo ............
Mustela .........
Putorius .........
Lutra ...........
LUTRONECTES ....
Enhydris ...........
Mellivora .......
MELES ...........
Alurus...
ALUROPUS

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* I am far from sure that what is here recognized as the “Mediterranean Province" should not be subdivided, and the Eastern or Persian division recognized as a "Persian Province". If the Eastern, Middle, and Western divisions of the North American Rogion are to be accorded the rank of “Provinces", it may be necessary to admit, on similar grounds, a “Japanese Province"; but I am not at present prepared to adopt these divisions as “Provinces". To make the Provinces of the North American and Europæo-Asiatic Regions more nearly co-ordinate, I should prefer to unite the Middle and Western Provinces of the North American Region as forming a single Province. In fact, it seems doubtful whether the North American Region is differentiated into primary divisions that should be regarded as having co-ordinate rank with the Mediterranean and Manchurian divisions of the Europæo-Asiatic Region.

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