Near die and Pahr arctic Regions. 



Do 



1 liave veiiturcMl to estaMi^li arc not to Ue regarded as exce})ti()ns. 

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

 members of groups exelusi\'ely American. 



'■ Secondly, the deficiency caused l)y the disappearance of char- 

 acteristic forms is ol)viated by a largc^ increase of the members 

 of genera feebl}' represented in the more temperate regions, and 

 also Ijy tlie introduction of many genera heretofore regarded as 

 confined to the northern part of Euroi)e and Asia. Among these 

 latter are many species which can be distinguished from tlieir 

 foreign analogues onl}' by the most careful examination. This 

 l)arallelism is sometimes most exact, running not merely through 

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

 are com])osed." ( r^ake Superior, l8o(). 2o^)-240. ) 



W . V. Kirl)y,in a paper "On the Geographical Distribution of 

 the Diurnal Lepidoptera as ct^npared with that of Birds,' states : 

 '• Had I been dealing with Tie])ido})tera only, I would certainly 

 liave united Dr. Sclater's ' r'ahearctic Region ' and " Nearctic 

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

 locera are seldom identical with those of northern Asia and 

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

 exce})t a few representatives of South American genera, which 

 have no more right to be considered Nearctic species than the 

 similar chance rein'esentatives of African forms in North Africa 

 or Southwest Euro})e, or of Indian forms in Southeast Euro})e, 

 havc'to be considered Pakearctic species." (Journ. Linnean Soc. 

 London, Zool. 1873, 432.) 



It now becomes evident that the so-called Pala'arctic and Ne- 

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

 coml)ining two wholly distinct regions — the Boreal with the So- 

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

 ran in Elurasia. Eliminating these austral elements as wholly 

 foreign to tlie region to wdiich the}' have been so persistentlv 

 attached, there remains a single great Circumpolar Boreal region 

 characterized 1)V a remarkablv 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 

 has been long acknowledged, 3'et from the very nature of the 

 case the resulting life regions must l)e different — the one supple- 



