518 Mr. P. L. Sclater on the Geographical 



there were good grounds for adopting this course. Mr. 

 Wallace, in his excellent chapter on zoological regions, has 

 gone fully into the arguments vipon this subject, and I will 

 not repeat them here. I admit with him that my six regions 

 are not of precisely equal rank, and that some of them are 

 far more isolated and better characterized than the others. 

 But I also maintain with him ''that, looker! at from every 

 point of view, they are more equal in rank than any others 

 that can be formed ; while in geograj.'hical equality, com- 

 ])actness of area, and facility of definition, they are beyond 

 all comparison better than any others that have yet been 

 proposed for the purpose of facilitating the study of geogra- 

 phical distribution.^^ 



After more than thirty-five years^ close attention to the 

 subject and a constant study of all that has been written 

 upon it by my brother workers, I am still convinced that, for 

 the study of vertebrate animals at least, this six-fold division 

 of the earth^s surface will be found to be more natural and 

 more convenient than any other arrangement that has yet 

 been suggested. On the present occasion, however, we are 

 engaged only with the Class of Birds, on the study of which 

 I originally based the six regions, and for which 1 maintain 

 they are eminently suitable. I will proceed now to take 

 these six regions one after the other, to point out some of 

 the principal characters which pertain to each of them, and 

 to mention the leading recent authorities to be referred to 

 by those who wish to gain an idea of the peculiarities of 

 their respective avifaunas. 



I. — The Pal.earctic Region {Regio Paltearctica). 



(a) Extent. — Africa north of the Atlas, Europe, Asia 

 jMinor, Persia and Asia generally north of the Himalayan 

 range, upper part of the Himalayan range, Northern Chinas 

 Japan, and the Aleutian Islands. 



(b) Characteristic Forms. — As I pointed out in my original 

 essay, before referred to, the Palsearctic or great Temperate 

 Region of the Old World is not so well supplied with peculiar 

 types as the remaining regions, and therefore, as regards its 



