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Baird says, that its fauna is almost identical with that of the Gila River, and has hardly any relation to that of Upper California. It possesses a considerable number (about twenty) of peculiar species of birds, but all belong to genera characteristic of the present sub-region; and there is no resemblance to the birds of Mazatlan, just across the gulf in the Neotropical region. Reptiles, Amphibia, and Fishes.—A large number of snakes and lizards inhabit this sub-region, but they have not yet been classified with sufficient precision to enable us to make much use of them. Among lizards, Iguanidae, Geckotidae, Scincidae, and Zonuridae, appear to be numerous; and many new genera of doubtful value have been described. Among snakes, Calamariidae, Colubridae, and Crotalidae are represented. Among Amphibia, Siredon, one of the Proteidae, is peculiar. The rivers and lakes of the Great Central Basin, and the Colorado River, contain many peculiar forms of Cyprinidae.
III. The Eastern or Alleghany Sub-region.
This sub-region contains examples of all that is most characteristic of Nearctic zoology. It is for the most part an undulating or mountainous forest-clad country, with a warm or temperate climate, but somewhat extreme in character, and everywhere abounding in animal and vegetable life. To the west, across the Mississippi, the country becomes more open, gradually rises, becomes much drier, and at length merges into the arid plains of the central sub-region. To the south, in Georgia, Florida, and Louisiana, a sub-tropical climate prevails, and winter is almost unknown. To the north, in Michigan and New England, the winters are very severe, and streams and lakes are frozen for months together. These different climates, however, produce little effect on the forms of animal life; the species to some extent change as we go from north to south, but the same types everywhere prevail. This portion of the United States, having been longest inhabited by Europeans, has been more thoroughly explored than other parts of North America; and to this more complete knowledge its superior zoological richness may be to some extent due; but there can be little doubt that it is also positively, and not merely relatively, more productive in varied forms of animal life than either of the other sub-regions.
Mammalia.—There seems to be only one genus absolutely peculiar to this sub-region—the very remarkable Condylura, or star-nosed mole, only found from Pennsylvania to Nova Scotia, and as far as about 94° west longitude. It also has opossums (Didelphys) in common with California, and three out of four species of Scalops, a genus of moles; as well as the skunk (Mephitis), American badger (Taxidea), racoon (Procyon), pouched rat (Geomys), beaver rat (Fiber), jumping mouse (Jaculus), tree porcupine (Erethizon), and other characteristic Nearctic forms.
Birds.—The birds of this sub-region have been carefully studied by American naturalists, and many interesting facts ascertained as to their distribution and migrations. About 120 species of birds are peculiar to the east coast of the United States, but only about 30 of these are residents all the year round in any part of it; the bird population being essentially a migratory one, coming from the north in winter and the south in summer. The largest number of species seems to be congregated in the district of the Alleghany mountains. A considerable proportion of the passerine birds winter in Central America and the West Indian Islands, and go to the Middle States or Canada to breed; so that even the luxuriant Southern States do not possess many birds which may be called permanent residents. Thus, in East Pennsylvania there are only 52, and in the district of Columbia 54 species, found all the year round, out of about 130 which breed in these localities; very much below the number which permanently reside in Great Britain.
This sub-region is well characterised by its almost exclusive possession of Ectopistes, the celebrated passenger pigeon, whose enormous flocks and breeding places have been so often described; and Cupidonia, a remarkable genus of grouse. The only Nearctic parrot, Conurus carolinensis, is found in the Southern States; as well as Crotophaga, a South American genus usually associated with the cuckoos. Helmintherus and Oporornis, genera of wood-warblers, may be considered to be peculiar to this sub-region, since in each case only one of the two species migrates as far as Central America; while two other genera of the same family, Siurus and Setophaga, as well as the finch genus, Euspiza, do not extend to either of the western sub-regions. Parus, a genus of tits, comes into the district from the north;0tocorys, an alpine lark, and Coturniculus, an American finch, from the west; and such characteristic Nearctic genera as Antrostomus (the whip-poor-will goatsuckers); Helminthophaga, Dendraeca, and Myiodioctes (wood-warblers); Vireo (greenlets); Dolichonya (rice-bird); Quiscalus (troupial); Meleagris (turkey); and Ortyx. (American partridge), are wide-spread and abundant. In Mr. J. A. Allen's elaborate and interesting paper on the birds of eastern North America, he enumerates 32 species which breed only in the more temperate portions of this province, and may therefore be considered to be especially characteristic of it. These belong to the following genera:—Turdus, Galeoscoptes, Harporhynchus, Sialia, Dendraeca, Wilsonia, Pyranga, Vireo, Lanivireo, Lophophanes, Coturniculus, Ammodromus, Spizella, Euspiza, Hedymeles, Cyanospiza, Pipilo, Cardinalis, Icterus, Corvus, Centurus, Melanerpes, Antrostomus, Coccyzus, Ortya, and Cupidonia. Reptiles—In this class the Eastern States are rich, possessing many peculiar forms not found in other parts of the region. Among snakes it has the genera Farancia and Dimodes belonging to the fresh-water snakes (Homalopsidae); the South American genus Elaps ; and 3 genera of rattlesnakes, Cenchris, Crotalophorus, and Crotalus. The following genera of snakes are said to occur in the State of New York :-Coluber, Tropidonotus, Leptophis, Calamaria, Heterodon, Trigonocephalus, Crotalus, Psammophis, Helicops, Rhinostoma, Pituophis, and Elaps. Among lizards, Chirotes, forming a peculiar family of Amphisbenians, inhabits Missouri and Mexico; while the remarkable glass-snake, Ophisaurus, belonging to the family Zonuridae, is peculiar to the Southern States; and the South American Sphaerodactylus, one of the gecko family, reaches Florida. Other genera which extend as far north as the State of New