HISTORICAL AND GEOGRAPHICAL
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Zoological Characteristics.—The close affinity of the Nearctic fauna with that of the Palsearctic Region has already been pointed out (see p. 5). The number of families of terrestrial Vertebrates represented in the Nearctic Region is 120, namely, 26 of Mammals, 59 of Birds, 21 of Reptiles, and 14 of Amphibians. This number is considerably below the corresponding one for the Palsearctic Region, but, on the other hand, while there are no peculiar families in the latter, the Nearctic Region possesses five, namely, the Haplodontidse (Sewellels) and Antilocapridse (Prongbuck) among Mammals; the Chamseidse (Wren-Tits) among Birds; the Aniellidse among Reptiles, and the Sirenidse (Mud-Eels) among Amphibians.
There are, besides, several peculiar genera of importance, of which Scalops (Web-footed Moles), Taxidea (American Badger), Haplocerus (Rocky Mountain Goat), and Ovibos (Musk Ox) may be taken as examples. The latter, however, was once a Palsearctic species, and occurred even in Britain. The American Bison (Bison bison), Grizzly Bear (Ursus horribilis), American Beaver (Castor canadensis), Wapiti Deer (Cervus canadensis), Moose (Alces americana), and the Caribou (Rangifer caribou) are also characteristic animals, while the families Geomyidse (Pocket Gophers) and Heteromyidse (Pocket Mice) &c. among Mammals; the Tetraonidse (Grouse) and Meleagridse (Turkeys) among Birds; the Xantusiidse among Reptiles; and the Desmognathidse among Amphibians, are more numerously represented in this region than elsewhere.
Californian Sub-region.—In this small area are found representatives of 86 families of terrestrial Vertebrates, as follows: Mammals, 21; Birds, 49; Reptiles, 8, and Amphibians, 8. The Californian is the only one of the Nearctic Sub-regions which possesses any families peculiar to itself. These are three in number, namely, the Haplodontidse (Sewellels), Chamseidse (Wren-Tits), and Aniellidse (a family of Lizards). Of characteristic families, though not peculiar, the Phyllostomatidse (Vampire Bats) and Noctilionidse (Free-tailed Bats) should be mentioned, while the genera Neurotrichus (Mole-Shrews) and Bassariscus (Cacomistles) are also to be placed in this category.
Rocky Mountain Sub-region. — This sub-region is the richest portion of the Nearctic Region, for it possesses representatives of 107 (out of 120) families of terrestrial Vertebrates. This number is made up as follows : Mammals, 25 ; Birds, 55 ; Reptiles, 18 ; and Amphibians, 9. Although there are no peculiar families in this area, yet there are several very characteristic genera, among which may be mentioned Antilocapra (the Prongbuck), Haplocerus (the Rocky Mountain Goat), Bison (the American Bison), and Cynomys (Prairie Dogs). The families Dicotylidse (Peccaries), Basypodidse (Armadilloes), Cotingidse (Chatterers), T׳rogo7iidse (Trogons), and Cracidse (Curassows) are examples of essentially Neotropical families which just enter this sub-region from the south, while, lastly, the Helodermatidse (Poisonous Lizards) are common to this area and the Mexican Sub-region.
Alleghany Sub-region.—The Eastern United States, forming this Sub-region, are to be regarded as the most characteristic portion of the Nearctic Region. Some 99 families of terrestrial Vertebrates are represented, as follows: Mammals, 18; Birds, 53; Reptiles, 16; and Amphibians, 12. No family is peculiar, and among Mammals there is only one genus that is confined to the Sub-region, namely, Condylura (Star-nosed Mole). The Bidelphidse (Opossums) are common to this and the Rocky Mountain Sub-regions, while the extreme south of Florida is the home of many typically Neotropical groups of animals. Examples of such may be found in the Phyllostomatidse (Vampire Bats); Coerebidse (Honey-Creepers); Aramidse (Courlans); the Frogs of the family Cystignathidse; the Land-Shells of the family Urocoptidse; and the Butterflies of the family Heli-conidse. The most interesting of the peculiar Birds are the celebrated Passenger Pigeon (Ectopistes migratorius) and the Carolina Parrot (Conuropsis carolinensis)—both on the verge of extinction—while other characteristic groups are the Meleagridse (Turkeys), and Sirenidse (Mud-Eels).
Canadian Sub-region.—In this sub-region only 75 families of terrestrial Vertebrates are represented, namely, 20 of Mammals, 44 of Birds, 3 of Reptiles, and 8 of Amphibians. It is thus the poorest section of the Nearctic Region, but at the same time an interesting feature of the fauna is presented by the number of genera and species which are common to it and the Palsearctic Region. Among these may be mentioned Cervus (Deer), Rangifer (Reindeer), Alces (Elk), Bison (Bison), Ovis (Sheep), Gulo (Gluttons), Mustela (Martens), Lemmus (Lemmings), Ursus maritimus (the Polar Bear), Vulpes lagopus (the Arctic Fox), and many birds. The genus Ovibos (Musk Ox) is now peculiar to the sub-region. The Reptiles and Amphibians are few, and of little importance. Lastly, certain genera of Butterflies, such as Parnassius, Colias, Ccenonympha, (Ends, and others, are well represented and characteristic.
Number of Families of terrestrial Vertebrates in the Nearctic Region and its Four Sub-regions.
	Mammals.	Birds.	Reptiles.	Amphibians.	Total.
Nearctic Region in General ...	26 (2)1	59(1)	21(1)	14(1)	120 (5)
Californian Sub-region	21 (1)	49(1)	8(1)	8	86 (3)
Rocky Mountain ,,	25	55	18	9	107
Alleghany ,,	18	53	16	12	99
Canadian ,,	20	44	3	8	75
1 The figures in parentheses indicate the number of peculiar families.
INSULAR FAUNAS.
The animal life on islands is of special interest to the student of zoogeography. As a rule the genera and species are much fewer in number than is the case in continental areas, but at the same time these are often remarkably peculiar and well defined. Before a detailed study of any
as a whole; and among the Reptiles and Amphibians the Bipsadomorphidse (Tree Snakes), Elapidse (Coral Snakes), Iguanidse (Iguanas, &c.), Tegidse (Greaved Lizards), Alligatoridse (Alligators and Caimans), Bendrobatidse (Solid-chested Tree-Frogs), Hylidse (Typical Tree-Frogs), Pipidse (Surinam Toad, &c.), and others.
Mexican Sub-Region.—In the richness of its fauna this Sub-region falls little short of the Brazilian, for it possesses representatives of 127 families of terrestrial Vertebrates. This number is made up as follows :	Mammals,
24; Birds, 67 ; Reptiles, 26 ; and Amphibians, 10. There is little peculiarity, only two families—both Reptilian—being confined to the sub-region, namely, Xenosauridse and Bermatemydidse (Mud-Terrapins), which contain only one and four species respectively. Characteristic of this area are two species of Tapir (Tapirus bairdi and dowi), which are the most northerly representatives of the family in the New World. The following families appear to have their metropolis in this Sub-region:—Procyonidse (Raccoons), Momotidse (Motmots), Odontophoridse (American Partridges), Anguidse (Slow-Worms), and Plethodontidse.
Antillean Sub-region.—Since this area is wholly made up of islands, most of which are small, it is hardly surprising to find that the number of families of terrestrial Vertebrates is much inferior to that in the other portions of the Neotropical Region. Some 76 families in all occur in the Sub-region. They are apportioned as follows :—Mammals, 7 ; Birds, 47 ; Reptiles, 16; and Amphibians, 6. Only two are peculiar, namely, one of Mammals, and one of Birds. These are the Solenodontidse (Solenodons), of which only a couple of species are known, and the Todidse (Todies), of which there are fire.
There is a remarkable absence of Mammals in this, as in other insular Sub-regions, for there are no Primates, Carnivora, Ungulata, or Edentata. The only Rodents are the Octodoniidse (Spiny Mice), represented by about half a dozen species of Capromys, a genus practically peculiar to the West Indies ; and a few Muridse belonging to the sub-family Sigmodontinse. The Birds are mainly of a Neotropical character, but the following important families are quite absent: Phytotomidse (Plant-Cutters), Pipridse (Mana-kins), Bendrocolaptidse (American Creepers), Formicariidse (Ant-Thrushes), Rhamphastidse (Toucans), Momotidse (Motmots), Cracidse (Curassows, &c.), Tinamidse (Tinamous), and Rheidse (Rheas). Lastly, among Butterflies, the typically Neotropical Brassolidse, Euselasiidse, Lemoniidse, and the genus Morpho, are totally unrepresented.
Number of Families of terrestrial Vertebrates in the Neotropical Region and its Four Sub-regions.
	Mammals.	Birds.	Reptiles.	Amphibians.	Total.
Neotropical Region in General	32 (10)1	80 (23)	29 (2)	14(4)	155(39)
Chilian Sub-region ...	23(1)	53 (1)	17	7	100 (2)
Brazilian ,,	27 (2)	71(4)	23	12(2)	133 (8)
Mexican ,,	24	67	26 (2)	10	127 (2)
Antillean ,,	7(1)	47 (1)	16	6	76 (2)
1 The figures in parentheses indicate the number of peculiar families.
VI. NEARCTIC REGION.
Extent.—The Nearctic Region embraces the whole of North America as far south as the Neotropical boundary, and the whole of Greenland.
Sub-regions.—Like all the other regions, the Nearctic is divided into four sub-regions, which are as follows:—(1) Californian; (2) Rocky Mountain; (3) Alleghany ; and (4) Canadian. The Californian Sub-region consists of a narrow strip of country, west of the Sierra Nevada and the Cascade range, and extending from Vancouver Island and part of British Columbia in the north almost to latitude 30° in the south. The Rocky Mountain Sub-region lies immediately to the east of the Californian, and includes the whole of the dry and elevated area covered by the mountains from which it takes its name. To the south it embraces Lower California and the Central Mexican plateau, while its eastern boundary begins on the coast a little to the north of the Rio Grande, runs up nearly due north to about the 50th parallel, then sweeps round to the north-west almost to the Little Slave Lake, thence southwards to near the source of the Missouri River, and finally westwards till it meets the boundary of the Californian Sub-region. The Alleghany Sub-region comprises the United States east of the last sub-region and south of the Great Lakes, and includes Nova Scotia. All the remaining portion of North America and Greenland constitute the great Canadian Sub-region.
Physical Features.—The Nearctic Region presents a great variety of physical features. Like the Palsearctic Region, it extends from beyond the Arctic Circle to the Northern Tropic, and hence has a great range of temperature. In the northern portion the winter temperature is much lower than is found at a corresponding latitude in Europe, and this is largely due to the great widening out of the land mass towards the Polar Regions. Add to this the extreme contraction of the area in its subtropical portion, and we have two principal reasons for the somewhat smaller variety in the forms of animal life as compared with the Palsearctic Region. The chief physical features of the region are the large lakes and inland seas in the north-eastern portion and the important ranges of mountains in the west. The latter run from north to south, and are practically a continuation of the great chain which runs through Central America and the west of South America. In the east are smaller ranges, constituting the so-called Appalachian Highland, while in the centre of this great continent is a vast extent of plain, which in the north is frozen and barren, between latitudes 50° and 60° covered with forest, and in the south dry, treeless desert. Greenland, the outlying portion of the Nearctic Region, is entirely arctic, and buried beneath a mass of ice of unknown thickness.