packarp.} GEOGRAPHICAL DISTRIBUTION OF PHYLLOPODA. 365 
so that to him is due the credit of first distinguishing the Central prov- 
ince. | 
In 1866, Professor Baird,! from a study of the avifauna of the United 
States, concluded that ‘the ornithological provinces of North America 
consist of two great divisions of nearly equal size in the United States, 
meeting in the vicinity of the one hundredth meridian, the western half 
divisible again into two, more closely related to each other than to the 
eastern, though each has special characters. These three sections form 
three great provinces to be known as the western, middle, and eastern ; 
or those of the Pacific slope; of the great basin, the Rocky Mountains 
and the adjacent plains; and of the fertile plains and region generally, 
east of the Missouri.” _ 
In 1871, Mr. J. A. Allen? divided the avifauna of the United States 
into two provinces, the eastern and western, the latter embracing the 
Pacific coast. Mr. Allen afterwards adopted Professor Baird’s division 
into three provinces. (The geographical distribution of the mammalia, 
ete. Bulletin of Hayden’s U. 8. Geographical and Geological Survey 
of the Territories, May 3, 1878.) 
In 1873,? Mr. W. G. Binney published a map of the distribution of 
our land shells, dividing the molluscan fauna into the Hastern, Central, 
and Pacific provinces. 
In 1875, Prof. E. D. Cope, in his check-list of North American Batra- 
chia and Reptilia,* divided the Nearctic realm of Sclater into the Aus: 
troriparian, Eastern, Central, Pacific, Sonoran, and Lower Californian 
regions. He remarks that “the Pacific region is nearly related to the 
Central, and, as it consists of only the narrow district west of the Sierra 
Nevada, might be regarded as a subdivision of it. It, however, lacks 
the mammalian genera Bos and Antilocapra, and possesses certain pecu- 
liar genera of birds, as Geococcyx, Chamea, and Oreortyx. . . . There 
are some genera of reptiles, e. g. Charina, related to the Boas, Lodia, 
Aniella, Gerrhonotus, and Xantusia, which do not occur in the central 
subregion. There are three characteristic genera of Batrachia, all 
Salamanders, viz: Anaides, Batrachoseps, and Dicamptodon; while the 
eastern genera Plethodon and Diemyctylus reappear after skipping the 
entire central district.” Cope adds that “‘the fresh-water fish fauna is 
much like that of the central district in being poor in types.” Cope’s 
Sonoran region is evidently a northward extension of the Central Ameri- 
can fauna, which sends its outliers into Southern Arizona, Utah, and 
New Mexico, and is not to be taken into account in discussing the faunal 
provinces of the United States alone. 
In 1876, Wallace, in his “Geographical Distribution of Animals,” di- 
vided the Nearctic region into four subregions, viz: the Californian, 
Central or Rocky Mountain, Alleghanian, and Canadian. His Central 
subregion extended to lat. 25° N. 
It will be seen from this review that by general consent the fauna of 
the Pacific slope is on the whole regarded as belonging to a separate 
province from that of the Rocky Mountain plateau, whether we regard 
the mammals, birds, reptiles, amphibians, Coleoptera, or land shells. 
Botanically, as observed by those who have traveled across the plains 
to California, the flora of the great plains is quite different from that of 
the Eastern States, and the Pacific flora is as distinct from the central 
flora. This has been clearly shown by Sir J. D. Hooker and Prof. Asa 
American Journal of Science and Arts, January and March, 1866. 
? Bulletin of the Museum of Comp. Zoology, April, 1871. 
a Catalogue of the Terrestrial Molluses of North America. Bull. Mus, Comp. Zool., 
1873. 
4Bulletin U. §. Nat. Mus., Washington, 1875. 
