182 MIGRATION AND DISTRIBUTION 



to be obtained only by the discovery of mare's nests, as 

 is the fashion nowadays.* 



He had much correspondence, always of a very 

 friendly nature, with Mr. Wallace, and so far as this 

 question is concerned, it ended with the following 

 letter : — 



Magdalene College, Cambridge, 



June 17, 1894. 



My dear Wallace, 



I thank you very much for the paper you have 

 sent me. I saw the title of it advertised and got a copy 

 of Natural Science accordingly — ^reading it with interest 

 but with no little regret, though I have no fault to find 

 with the way in which you defend your position and 

 attack mine. Indeed, I highly appreciate your delicacy 

 and feel sure of your wish to do nothing but bring out 

 the truth. I should much like to reply to you, but I 

 really don't know when I can find time to do so. I am 

 off on Tuesday for a three weeks' holiday beyond the 

 j-each, I hope, of posts. I will only remark now that you 

 proceed on the supposition that my " Holarctic " Region 

 =your Palsearctic and Nearctic — whereas the southern 

 boundaries of this last are, in my opinion and that of 

 several American zoologists, very uncertain — ^though to 

 me it is clear that the Neotropical Region extends much 

 more to the northward than you would have it run — and 

 probably the same is to be said of the Indian Region. 

 Thus a very considerable number of the genera, which 

 you assign to your Nearctic and Palaearctic Regions, 

 belong really to more southern areas, and by their 

 elimination your lists would present a very different 

 aspect. Again, too, you have omitted from your Nearctic 

 list all the Palaearctic genera of birds which inhabit 

 Alaska, and if I am not mistaken there are several 

 Mammals also, making Alaska essentially Palaearctic. 

 There are also not a few other (as it seems to me) 

 inaccuracies, which would make no small change. 



* letter to Canon H. B. Tristram, February 16, 1889. 



