LITERARY WORK, ETC. 211 



Sclater are, for all practical purposes of the study of distribu- 

 tion, the most convenient and those which best illustrate the 

 actual facts of nature — was contested bv mv friend, Professor 

 Alfred Newton, as regards the Nearctic and Palaearctic regions, 

 which he contended formed but one natural region. I therefore 

 thought it necessary to go into the subject in more detail, and 

 contributed a paper to Natural Science in the following June, 

 entitled " The Palaearctic and Nearctic Regions compared as 

 regards the Families and Genera of their Mammalia and 

 Birds." 



The first of these papers was for the purpose of showing 

 that, to be of any practical use to- naturalists, zoological regions 

 must be so defined as to serve to elucidate the distribution of 

 all land animals. This will be evident if we consider the 

 results of the contrary view, that many classes, orders, and 

 even families, require a special set of regions to exhibit their 

 distribution with any approach to accuracy. Now as there 

 are some hundreds of these groups in the animal kingdom, we 

 should, perhaps, require fifty or a hundred sets of zoological 

 regions — each set differing in the number of regions and in 

 the boundaries of each, involving a different set of names in 

 each case. The result would be that each specialist would 

 have his own set of regions, with different names and different 

 boundaries ; and as no one could be familiar with all these, the 

 conclusions of each would be unintelligible and useless to 

 others. With one set of regions, on the other hand, the distri- 

 bution in every case can be described in terms which would 

 be intelligible to all ; and the comparison of the distribution 

 of groups differing in powers of dispersal and in other ways, 

 would often lead to an explanation of the differences of dis- 

 tribution, which is the whole end and aim of the study, and 

 which, so far as I can see, can be arrived at in no other way. 



The second and more technical paper was for the purpose 

 of showing the great importance of the absence of extensive 

 groups from one region that are present in the adjacent region, 

 even though these groups are not peculiar to either. Thus, 

 the fact that both the bear and the deer families are absent 

 from Africa south of the Sahara, though abundant throughout 



