226 Brewster on Birds of Bort Walla Walla , W. T. 
As an exponent of the workings of geographical variation in 
species easily modified by their surroundings, this material is 
especially instructive. The region represented apparently con- 
stitutes a sort of neutral ground between the Pacific and Middle 
Provinces and naturally its fauna is a mixed one. Setting aside 
species not subject to geographical modification, and 'migrants 
from the north which have only an indirect bearing on the 
general question, we find the collection divisible into three 
classes: (i) Forms identical with or most nearly like Pacific 
coast types; (2) Forms about intermediate between representa- 
tives inhabiting the Pacific and Middle Provinces ; (3) Forms to a 
certain extent intermediate between Pacific and Middle Province 
representatives, but differing from both in certain original char- 
acteristics. The locality seems to be nearly lacking in typical 
representatives of the Middle Province ; and its fauna, on the 
whole, must be regarded as closely related to that of the coast 
region. 
The third class, although least numerous, includes many of the 
most interesting birds. The majority of these are resident forms, 
a fact which sufficiently explains many of their peculiarities, for 
it is well known that sedentary species are, of all others, the most 
subject to local variation. 
But while the philosophic bearing of this material is not 
doubtful, there are certain systematic difficulties in the way of 
its satisfactory presentation. I refer to the naming of these in- 
termediate forms. The practice has been to use the name of the 
race to which the bird seems most nearly related, and this I have 
been forced to adopt in default of a better 'way. But the method 
obviously fails to meet the requirements of such cases, whjle to 
a certain extent it is unscientific and inaccurate. The evil, how- 
ever, is not likely to be remedied, for it is difficult to conceive 
of a system of nomenclature that would adequately designate the 
numberless intermediate and local types. 
In the present connection I would gratefully mention the 
assistance received from my friend, Mr. Ridgway, who, during 
my study of the collection, has given me every facility for exam- 
ining the matchless series in the National Museum, and to whom 
I am further indebted for many valuable suggestions. My obli- 
gations to Capt. Bendire are greater than I can adequately ex- 
press, for, in addition to other kind attentions, he has generously 
