illustrating the Distribution of Marine Animals. 219 



Iceland, the temperature is at least ten degrees warmer than 

 in the corresponding latitude of the South Pacific, and thir- 

 teen or fourteen degrees warmer than in the same latitude 

 in the South Atlantic* 



The influence of so warm an ocean on the temperature of 

 Britain, and on its living productions, animal and vegetable, 

 is apparent, when it is considered that the winds take the 

 temperature nearly of the waters they pass over. And the 

 effects on the same region that would result from deflecting 

 the Gulf Stream in some other direction, as brought out by 

 Prof. Hopkinst and others, and substituting in the Northern 

 Atlantic the temperature of the Southern Atlantic, is also 

 obvious, without further illustration. The discussion of these 

 subjects would be foreign to the topic before us. 



The subdivision of the oceans into Temperature Regions 

 affords a convenient means of dividing off the coasts into 

 Zoological Provinces. A comparison of the facts afforded 

 by the distribution of Crustacea, with the positions and ex- 

 tent of the provinces thus deduced, shew that they are natu- 

 ral, and may in general be well characterized. 



Zoological Provinces have been considered by some as 

 centres of creation, and therefore of diffusion, for groups of 

 species. But such kinds of centres we fail to distinguish in 

 any part of the globe. Each species may have had its one 

 point of origin and single centre of diffusion in many and 

 perhaps the majority of cases : but however the fact may be, 

 we have no evidence for asserting that particular regions were 

 without life, and were peopled by migration from specific and 

 predetermined centres ; for if there were such centres of dif- 

 fusion, there are at present no means by which they may be 

 ascertained. The particular temperature region in which a 



* Ross, in his antarctic voyage, found the sea-temperature in 60° south and 

 3° west, 31 £° F., in the month of March ,• at the South Shetlands, 61° south, 

 the sea-temperature was 31° to 35° in January (midsummer) ; and in the same 

 latitude, and 45° west, it was 30-1° in February. 



t Quarterly Jour. Geol. Soc, vol. viii., p. 56, and Amer. Jour. Science, 1853, 

 vol. xv. 



