EASTERN AND WESTERN FORMS OF THE NUTCRACKER. 445 
their ranges meet, for there is no evidence that in any part of the 
whole Palearctic Region breeding localities of the slender-billed 
race are situated north of those of the thick-billed form on 
approximately the same degree of longitude, unless Mr. Seebohm 
be correct in referring the Japanese specimens to the typical 
form. In fact, this identification by Mr. Seebohm seems to be 
the only foundation for his theory of an arctic and a temperate 
race, aS opposed to Blasius’s of a western and eastern. Upon 
a proper reference of the Japanese specimens, therefore, hinges 
the whole question. 
I have before me four examples from Japan, which I can 
compare with four from Korea, one from Kamtschatka, and a 
number of both forms from Europe. According both to Blasius 
and Seebohm, the slender-billed individuals from Western Europe 
are only immigrants from Siberia; they will consequently serve 
as well as specimens’from the latter country. 
Both Blasius and Seebohm lay considerable stress on the 
dimensions of the bills as indicating the subspecific difference. 
To a certain extent this is so, but only if the specimens can be 
examined at the same time, for it is plain when inspecting a series 
of these birds that the peculiar shape of the bills in the two birds 
is of more importance than the leugth and the height. In the 
typical form the upper mandible is more swollen, the upper 
tomium more inflected, and the basal portion of the culmen 
straighter and more parallel with the commissure, while in the 
slender-billed form the upper tomium is hardly inflected at all, 
and the culmen tapers at once towards the tip from the frontal 
feathering. At the latter point the bills of both forms are nearly 
of the same height, and consequently Dr. Blasius’s method of 
measuring the bills in the middle is more expressive than that of 
Mr. Seebohm, who measures them at the angle of the gonys. It 
is plain that this difference is easier to appreciate in the specimens 
than to express in words or condense into a satisfactory diagnosis, 
the more so since the bills in these birds are subject to consider- 
able individual variation in all directions. I will also call attention 
to the fact that the bills of the resident birds of Kurope seem to 
vary to some extent locally, as both Blasius and Von Tschusi- 
Schmidhoffen have noted a difference in the stoutness of the bill 
in specimens from Sweden and from the Alps. 
The other character to which Blasius has culled special 
