Near die and Pali far die Regions. 63 



1 have ventured to establish arc not to be regarded as exceptions, 



They are all closely allied to European forms, and by no means 

 members of groups exclusively American. 



'' Secondly, the deficiency caused by the disappearance of char- 

 acteristic forms is obviated by a large increase of the members 

 of genera feebly represented in the more temperate regions, and 

 also by the introduction of many genera heretofore regarded as 

 c< m lined to the northern part of Europe and Asia. Among these 

 latter are many species which can be distinguished from their 

 foreign analogues only by the most careful examination. This 

 parallelism is sometimes most exact, running not merely through 

 the genera, but even through the respective species of which they 

 are composed." (Lake Superior, 1850, 239-240.) 



\Y. F. Kirby, in a paper ' On the Geographical Distribution of 

 the Diurnal Lepidoptera as compared with that of Birds,' states : 

 " Had I been dealing with Lepidoptera only, I would certain! v 

 have united Dr. Selater's ' Palsearctic Region ' and ' Nearctic 

 Region;' for although 'the species of North American Rhopa- 

 locera are seldom identical with those of northern Asia and 

 Europe, still the genera are the same with scarcely an exception, 

 except a few representatives of South American genera, which 

 have no more right to be considered Nearctic species than the 

 similar chance representatives of African forms in North Africa 

 or Southwest Europe, or of Indian forms in Southeast Europe, 

 have to be considered Palaearctic species*." (Journ. Linnean Soc. 

 London, Zool. 1873, 432.) 



It now becomes evident that the so-called Palaearetie and Ne- 

 arctic regions are the result, in each case, of confounding and 

 combining two wholly distinct regions the Boreal with the So- 

 noran in America and the Boreal with the analogue of the Sono- 

 ran in Eurasia. Eliminating these austral elements as wholly 

 foreign to the region to which they have been so persistently 

 attached, there remains a single great Circumpolar Boreal region 

 characterized by a remarkably homogeneous fauna, covering the 

 northern parts of America and Eurasia, 



Cope has shown that the chief differences between Boreal 

 America and Boreal Eurasia are found among the fishes and 

 batrachians animals living wholly or in part in water. Now it 

 cannot be insisted too strongly that while the chief factor in the 

 distribution of aquatic animals and plants is temperature, as 

 lias been long acknowledged, yet from the very nature of the 

 ease the resulting life regions must be different the one supple- 



