64 THE ZOOLOGIST. 



eye a feature unnoticed by others may appear conspicuous — 

 "Man sieht nur was man weiss." Even the most inveterate 

 " splitter " has some grounds for his subspecies, and it is hardly 

 fair to condemn his work without a knowledge of the material upon 

 which it is based. When one looks over a large series of skins 

 of a compound species so arranged that the geographical com- 

 ponents are separated by spaces, it is possible to appreciate at a 

 glance differences that are most difficult to state formally in 

 diagnoses (c/. Dr. J. A. Allen, 'Science,' n.s., xvi. pp. 383-386). 

 It should not be required for the institution of a subspecies that 

 it be conspicuously different from others. A character or com- 

 bination of characters, however small in amount, is sufficient if 

 thereby we can distinguish a form, but it is essential that the 

 character be supported by adequate material. Opponents of sub- 

 species are not alone in deploring the practice of founding new 

 forms upon one or two specimens ; sometimes, indeed, without 

 comparing them with reference to sex or date. 



In giving recognition to characters that are small in amount 

 but constant, the "splitter" is rendering a service to science, for 

 we may expect to gain a truer view of the derivative origin of 

 species by attending to the smaller and more immediate products 

 of variation, rather than to the larger and more remote. 



There seems to be a widespread feeling that, if subspecies are 

 persisted in, it will be injurious to the study of birds (cf. ' Ibis,' 

 1904, p. 660). It is easy to reply to this argument by referring 

 to the United States, where subspecies are much attended to. No 

 one will affirm that their recognition in that country has had 

 this effect. 



The non-recognition of subspecies often causes important 

 points in distribution to be overlooked. As an instance it may 

 be mentioned that two forms of Nutcracker are known to visit 

 this country, but they are usually placed together under the name 

 Nucifraga caryocatactes. There is reason to believe that the 

 majority of recorded specimens refer to the eastern form, N. 

 caryocatactes macrorhynchos, Brehm, and that the western repre- 

 sentative, N. caryocatactes caryocatactes (Linn.), is of very in- 

 frequent occurrence. It is clearly of importance to distinguish 

 these two forms so that we may know whence any Nutcracker 

 that may visit us has wandered. 



