54 ESSAY ON CLASSIFICATION. 



not identical with those of the arctic regions 1 And why 

 should a further increase of the average temperature in- 

 troduce such completely new types, when even in the 

 Arctics there are, where the different continents converge 

 towards the North Pole, such strikingly peculiar types 

 (Rhytina, for instance,) combined with those which are 

 identical over the whole arctic area r i l 



It may, at first sight, seem very natural that the arctic 

 species should extend over the three northern continents 

 converging towards the north pole, as there can be no 

 insuperable barrier to the widest dissemination over this 

 whole area of the animals that live in the glacial ocean, 

 or upon parts of three continents which are almost bound 

 together by ice. Yet, the more we trace this identity in 

 detail, the more surprising does it appear, as we find in 

 the Arctics as well as everywhere else, representatives of 

 different types living together. The arctic Mammalia, be- 

 longing chiefly to the families of Whales, Seals, Bears, 

 Weasels, Foxes, Ruminants and Kodents, have, as Mam- 

 malia, the same general structure as the Mammalia of any 

 other part of the globe, and so have the arctic Birds, the 

 arctic Fishes, the arctic Articulata, the arctic Mollusks, 

 the arctic Eadiata, when compared with the representa- 

 tives of the same types all over our globe. This identity 

 extends to every degree of affinity among these animals, 

 and the plants which accompany them : their orders, 



1 I beg not to be misunderstood, under consideration. Too little atten- 



I do not impute to all naturalists the tiou has thus far been paid to the 



idea of ascribing all the differences facts bearing upon the peculiarities 



or all the similarities of the organic of structure of animals in connexion 



world to climatic influences ; and I with the range of their distribution, 



wish only to remind them that even Such investigations are only begin- 



the truest picture of the correlations ning to be made, as native investi- 



of climate and geographical distri- gators are studying comparatively 



butiou does not yet touch the ques- the anatomy of animals of different 



tion of origin, which is the point continents. 



