York are, Scincus, Tropidolepis, Plestiodon, Lygosoma, Ameiva, and Phrynosoma.

Tortoises, especially the fresh-water kind, are very abundant; and the genera Aromochelys, Chelydra, Terrapene, and Trionyx, are nearly, if not quite, confined to this division of the region.

Amphibia.-Almost all the remarkable forms of Urodela, or tailed batrachians, peculiar to the region are found here only; such as Siren and Pseudobranchus, constituting the family Sirenidæ ; Menobranchus, allied to the Proteus of Europe; Amphiuma, an eel-like creature with four rudimentary feet, constituting the family Amphiumidæ; Notopthalmus, Desmognathus, and Menopoma, belonging to the Salamandrida; together with several other genera of wider range. Of Anura, or tail-less batrachians, there are no peculiar genera, but the Neotropical genus of toads, Engystoma, extends as far as South Carolina.

Fishes. Owing to its possession of the Mississippi and the great lakes, almost all the peculiar forms of North American fishes are confined to this sub-region. Such are Perca, Pileoma, Huro, Bryttus, and Pomotis (Percida); the families Aphredoderidæ and Percopsida; several genera of Cyprinodontidæ and Cyprinidae; and the family Polydontidæ.

Islands of the Alleghany Sub-region.

The Bermudas.-These islands, situated in the Atlantic, about 700 miles from the coast of Carolina, are chiefly interesting for the proof they afford of the power of a great variety of birds to cross so wide an extent of ocean. There are only 6 or 8 species of birds which are permanent residents on the islands, all common North American species; while no less than 140 species have been recorded as visiting them. Most of these are stragglers, many only noticed once; others appear frequently and in great numbers, but very few, perhaps not a dozen, come every year, and can be considered regular migrants. The permanent residents are, a greenlet (Vireo noveboracensis), the catbird (Galeoscoptes carolinensis), the blue bird (Sialia sialis), the cardinal (Cardinalis virginianus), the American crow (Corvus

americanus), and the ground dove (Chamapelia passerina). The most regular visitants are a kingfisher (Ceryle alcyon), the woodwagtail (Siurus noveboracensis), the rice-bird (Dolichonyx oryzivorus), and a moorhen (Gallinula galeata). Besides the American species, four European birds have been taken at the Bermudas: Saxicola ananthe, Alauda arvensis (perhaps introduced), Crex pratensis, and Scolopax gallinago.

A common American lizard, Plestiodon longirostris, is the only land reptile found on the islands.

IV. The Sub-Arctic or Canadian Sub-region.

This sub-region serves to connect together the other three, since they all merge gradually into it; while to the north it passes into the circumpolar zone which is common to the Palæarctic and Nearctic regions. The greater portion of it is an extensive forest-district, mostly of coniferæ; and where these cease towards the north, barren wastes extend to the polar ocean. It possesses several northern or arctic forms of Mammalia, such as the glutton, lemming, reindeer, and elk, which barely enter the more southern sub-regions; as well as the polar bear and arctic fox; but it also has some peculiar forms, and many of the most characteristic Nearctic types. The remarkable musk-sheep (Ovibos) is confined to this sub-region, ranging over a considerable extent of country north of the forests, as well as Greenland. It has been extinct in Europe and Asia since the Post-pliocene epoch. Such purely Nearctic genera as Procyon, Latax, Erethizon, Jaculus, Fiber, Thomomys, and Hesperomys, abound, many of them rauging to the shores of Hudson's Bay and the barren wastes of northern Labrador. Others, such as Blarina, Condylura, and Mephitis, are found only in Nova Scotia and various parts of Canada. About 20 species of Mammalia seem to be peculiar to this sub-region.

Plate XX. Illustrating the Zoology of Canada. We have here a group of Mammalia characteristic of Canada and the colder parts of the United States. Conspicuous in the foreground is the skunk (Mephitis mephitica), belonging to a genus of the weasel family found only in America. This animal is VOL. II.-10

celebrated for its power of ejecting a terribly offensive liquid, the odour of which is almost intolerable. The skunks are nocturnal animals, and are generally marked, as in the species represented, with conspicuous bands and patches of white. This enables them to be easily seen at night, and thus serves to warn larger animals not to attack them. To the left is the curious little jumping mouse (Jaculus hudsonius), the American representative of the Palearctic jerboa. Climbing up a tree on the left is the tree porcupine (Erethizon dorsatus), belonging to the family Cercolabida, which represents, on the American continent, the porcupines of the Old World. In the background is the elk or moose (Alces americanus), perhaps identical with the European elk, and the most striking inhabitant of the northern forests of America, as the bison is of the prairies.

Birds. Although the Canadian sub-region possesses very few resident birds, the numbers which breed in it are perhaps greater than in the other sub-regions, because a large number of circumpolar species are found here exclusively. From a comparison of Mr. Allen's tables it appears, that more than 200 species are regular migrants to Canada in the breeding season, and nearly half of these are land-birds. Among them are to be found a considerable number of genera of the American families Tyrannidæ and Mniotiltidæ, as well as the American genera Sialia, Progne, Vireo, Cistothorus, Junco, Pipilo, Zonotrichia, Spizella, Melospiza, Molothrus, Agelæus, Cyanura, Sphyrapicus, and many others; so that the ornithology of these northern regions is still mainly Nearctic in character. Besides these, it has such specially northern forms as Surnia (Strigidæ); Picoides (Picidæ); Pinicola (Fringillida); as well as Leucosticte, Plectrophanes, Perisoreus, and Lagopus, which extend further south, especially in the middle sub-region. No less than 212 species of birds have been collected in the new United States territory of Alaska (formerly Russian America), where a humming-bird (Selasphorus rufus) breeds. The great majority of these are typically American, including such forms as Colaptes, Helminthophaga, Siurus, Dendræca, Myiodioctes, Passerculus, Zonotrichia, Junco, Spizella, Melospizpa, Passerella, Scoleophagas, Pediocetes, and Bonasa;