378 BULLETIN OF THE 



embracing whole families, none of whose representatives are found oui- 

 side of the torrid zone of a single continent. Others are again equally 

 at home in the torrid and warm temperate zones, but which do not exist 

 either in the arctic or cold temperate zones ; others range throughout 

 the temperate and subtorrid. Nearly an equal number, some tropical, 

 but the greater part temperate species, range across continental areas, 

 within which, however, they are restricted. A great number of others 

 find their range limited in longitude to the half or the third of a conti- 

 nent, and others within still more circumscribed boundaries, fluviatile 

 species being frequently confined to single river basins. Through this 

 diversity of geographical range we have what may be termed cosmopoli- 

 tan, semi-cosmopolitan, circumpolar, continental, semi-continental, and 

 (relatively speaking) restricted species. The circumpolar and the conti- 

 nental are again realm species, the semi-continental and restricted, prov- 

 ince species. Rarely is any species limited to a narrower area than that 

 of two or three fauna; or flora;. Hence fauna; and flora; — which terms, 

 in their restricted sense, are properly applied only to the smallest of 

 the onto-geographical divisions — are determined by the peculiar associa- 

 tion of species, and not by the range of a single or of a few " restricted " 

 species ; hence by their general facies. Provinces, and realms, on the 

 other hand, may have species, and even genera and families, exclusively 

 distinctive of them. As there are cosmopolitan, circumpolar, continental, 

 and other kinds of species, so there must be cosmopolitan, circumpolar, 

 continental, and other kinds of genera and families ; the latter, as well 

 as species, having each a definite or specific geographical range as dis- 

 tinctive of them as any biological or anatomical character may be. They 

 are each circumscribed within definite areas, beyond which their 

 special adaptation to their natural surroundings forbids their extension, 

 unless aided by extraneous and unusual circumstances. 



The three divisions of zones, realms (or " regions"), provinces, and 

 fauna' and flora-,* comprise the phyto-zoblogic divisions usually recog- 



* Z>me, realm, region, kingdom, and province, are forms which have been used by dif- 

 ferent authors to designate the primary natural-history divisions of the earth's surface. 

 In deciding as to which of those terms should be exclusively applied to these divisions, 

 not only priority of use, but appropriateness, should of course be considered, and also the 

 sense in which they are at present currently employed, in order to avoid, as far as pos- 

 sible, the confusion necessarily attending changes of nomenclature. So far as priority 

 is concerned, zone undoubtedly has the precedence, it having boon u-ed for animals by 

 Wagner in 1844, by Agassiz in 1845, and much earlier than this by Humboldt and ot 

 in relation to the distribution of plants. It is, however, not always a strictly convenient 



