PACKAED.] GEOGEAPHICAL DISTRIBUTION OF PHYLLOPODA. 363 



portions of Arctic America, and of ISTortlieru Mexico, a region exposed 

 to great summer heats, winter cold, to long droughts, sadden rainbursts, 

 and other meteorological extremes. And it is interesting to notice that 

 the larger proportion of the Old-world forms are likewise restricted 

 to Eastern and Southern Europe, to the Mediterranean region, and to 

 Central and Northern Asia, i. e , to Mr. Sclater's "Paloe-arctic Eegion." 

 The Western European species are few in number, as in the Eastern 

 United States. In Africa the Phyllopods are restricted to the northern 

 portions of the continent, which are more or less elevated, dry, and 

 arid, as Algeria, Egypt, and Abyssinia, or to the Cape of Good Hope 

 (Capeland), while but a few, and those species of Ustheria, have been 

 Ibrought from the "Oriental Eegion" in Asia, and few from the ^lilthi- 

 opian Eegion" in Africa. Apus himalayanus, described by us from the 

 Himalaya Mountains, is evidently a member of the Central Asiatic or 

 Manchurian province, and not of the Indian region, while A. dulcianus 

 is reported from Afghanistan. 



Of purely tropical forms there are two species of Apus, one living 

 in St. Domingo, another in the island of St. Vnicent, while a species of 

 Eulimnadia exists in St. Domingo, and a species of Estheria flourishes 

 in Cuba. The Mexican forms are plateau species, while none have 

 yet been described from Central America. Two species of Ustheriah'dvO) 

 been described from South America. 



The map accompanying this memoirl represents the principal faunal 

 divisions of ISTorth America, with the isothermal lines of 32^, 40°, 60°, and 

 72°. The American continent is divided into — 



1. The Arctic Eealm and its Alpine outliers. 



2. Boreal province and its AUeghanian outliers. 



3. The Atlantic or Eastern province. 



4. The Central province. 



5. The Western or Californian province. 



6. The Antillean region. 



There are no species from the Central American province. 

 i 



THE AIVIEEICAN ARCTIC PROVINCE. 



This is a more or less natural subdivision of the Arctic or Circumpolar 

 Eealm, which includes the coast of Labrador, the northern shores of 

 Hudson's Bay, and the Arctic coast of jSTorth America, north of the 

 sothermal of 32° around to Bering's Strait and Greenland. We reject 

 the term "Nearctic" i)roposed by Mr. P. L. Sclater, and adopted by Mr. 

 A. E. Wallace, for America north of Central America, for the reason 

 that it seems to us an unnatural and artificial term. The fauna is 

 essentially American north temperate, while the Arctic regions of 

 America and Europe-Asia form a realm by itself, of much less impor- 

 tance, it is true, than the north temperate realm (American and Europseo- 

 Asiatic regions), when we consider the land plants and animals, but of 

 nearly as much importance as regards marine life. To apply the term 

 Nearctic to so vast a region as the American involves the idea that the 

 region covers an area essentially arctic in its features. It is to be hoped 

 that the term will not be adopted by American writers, as it is not 

 by German aisd French writers, and we heartily indorse Mr. J. A. 

 Allen's protest against the use of the term by American writers on this 

 subject. The circumpolar or Arctic realm is a realm by itself, limited by 

 the low degree of temperature and mainly bounded by the isothermal of 

 32°, and the adoption of this term will conduce, it appears to us, to 



