The Palaearctic and the Nearctic. But to justify such a division it is necessary to establish either an exclusive possession or a marked predominance of types in the one which are correspondingly deficient in the other.
Thus comparing the Nearctic and Palaearctic floras we find striking differences overlying the points of agreement already indicated.
In some cases, such as the Ethiopian and Neotropical and the Palaearctic and Nearctic regions, the faunas, although distinct, are related, several forms on opposite sides of the Atlantic being analogous, e.g.
These facts have led some naturalists to include the Palaearctic and Nearctic regions in one, termed Holarctic, and to suggest transitional regions, such as the Sonoran, between North and South America, and the Mediterranean, between Europe and Africa, or to create sub-regions, such as Madagascar and New Zealand.
Sclater' was the first to divide the world into a few great " regions," the Palaearctic, Ethiopian, Indian and Australian forming one group, the " Old World " (Palaeogaea); and the Nearctic and Neotropical forming a second, the New World (Neogaea).
The Nearctic and the Palaearctic. The reduction of the Oriental to a subregion, with consequent " provincial " rank of its main subdivisions, will probably be objected to, but these are matters of taste and prejudice.
Holarctic Region 5 Nearctic C Arctogaea Palaearctic () I V.
- Excepting towards the north, where, in Mexico, it meets, and inosculates with the Nearctic subregion, the boundaries of the Neotropical region are simple enough to trace, comprehending as it does the whole of South America and all Central America; besides including the Falkland islands to the south-east and the Galapagos under the equator to the west, as well as the Antilles or West India islands up to the Florida channel.
This is a state of things which exists nowhere else; for except in Australia, where a few indigenous and peculiar low non-Oscines are found, and in the Nearctic country, whither one family of Clamatores, viz.
Of families we find twenty-three, or maybe more, absolutely restricted thereto, besides at least eight which, being peculiar to the New World, extend their range into the Nearctic region, but are there so feebly developed that their origin may be safely ascribed to the southern portion of America.
First in point of importance comes the extraordinarily beautiful family of humming-birds (Trochilidae), with nearly 150 genera (of which only three occur in the Nearctic region) and more than 400 species.
There is no family of birds common to the Nearctic area and the Antillean subregion without occurring also in other parts of the Neotropical region, a fact which proves its, affinity to the latter.
(C) Arctogaea is Huxley's well-chosen term for all the rest of the world (including the Nearctic, Palaearctic, Indian and Ethiopian regions of P. L.
Faunistically, although not geographically, the Nearctic and Palaearctic areas must form the two subdivisions of one great unit, for which the " Holarctic region " is now the generally accepted term.
The following groups may be mentioned as characteristic and typically American, and, since we consider them as comparatively recent immigrants into the Neotropical region, as originally peculiar to the Nearctic area: Mniotiltidae, Vireonidae, Icteridae, Meleagris and various Tetraoninae.
" More than one-third of the genera of Nearctic birds are common also to the Palaearctic subregion.
If we take the number of Nearctic species at 700, which is perhaps an exaggeration, and that of the Palaearctic at 850, we find that, exclusive of stragglers, there are about 120 common to the two areas.
Nearly 20 more are properly Palaearctic, but occasionally occur in America, and about 50 are Nearctic, which from time to time stray to Europe or Asia.
The first of these supports Newton's contention of the essential unity of the Nearctic and Palaearctic areas.
In any case the various Nearctic subdivisions completely merge into each other, just as is to be expected from the physical configuration and other bionomic conditions of the North American continent.
Not indeed altogether so homogeneous as the Nearctic area, it presents, however, even at its extreme points, no very striking difference between the bulk of its birds.
Like the Nearctic the Palaearctic subregion seems to possess but one single peculiar family of land birds, the Panuridae, represented by the beautiful species known to Englishmen as the bearded titmouse, Panurus biarmicus.
We should have four great realms:-(1) Europe and Northern and Temperate Asia, Africa north of the Sahara (palaearctic region) and North and Central America (nearctic region); (2) Africa and South-Eastern Asia (Ethiopian and Indian region); (3) South America (neotropical region); and (4) Australia (Australian region).
With three exceptions, all the genera of this extensive family belong to the New World, being specially characteristic of the Neotropical region, where they occur as far south as Patagonia, while extending northward into the warmer parts of the Nearctic regions as far as California and British Columbia.
No parrot has recently inhabited the Palaearctic Region,' and but one (the Conurus carolinensis, just mentioned) probably belongs to the Nearctic; nor are parrots represented by many different forms in either the Ethiopian or the Indian Regions.
G..Gmelin, Giildenstalt, Lepechin and others - in the exploration of the recently extended Russian empire supplied not only much material to the Commentarii and Acta of the Academy of St Petersburg, but more that is to be found in their narratives - all of it being of the highest interest to students of Palaearctic or Nearctic ornithology.
Of these 128 are common to the Nearctic subregion.
It will therefore be seen from the above that next to the Nearctic area the Palaearctic has a much greater affinity to any other, a fact which might be expected from geographical considerations.