Henshaw on P. oc.cidentalis and P. clarkii. 2I*J 
when differently colored, two specimens rarely agree in the extent 
of the colored area. In some the white or gray extends in a 
broad area from the bill to behind the eye. In others it is limited 
to a narrow line reaching only to the eye. 
Although in the table the bills of several specimens are given 
as straight, it is rare to find two birds with the bills alike, and 
it is evident that it needs only a large number of specimens to 
constitute a series leading from one extreme to the other. 
None of the above specimens chance to equal the extreme size 
often attained by occidentalism and, on the other hand, specimens 
of clarkii may be had somewhat smaller than here given, yet 
the larger and smaller individuals in the list are quite within the 
requirements of size of their respective forms. 
As but eleven specimens are considered here, it is easy to 
understand to what an unlimited extent the characters of the two 
forms may be intermingled even when, as in the present instance, 
the birds are derived from the same locality and taken during the 
same season. 
Regarding the distinctive distribution of the two forms, we 
have little to offer save conjecture. The original specimens 
of both forms came from the Pacific coast, where the two are 
found together, at least in winter and during the migrations. 
Dr. Coues says “both varieties occur together in the United 
States west of the Rocky Mountains.” This was probably a 
slip of the pen, since Dr. Coues clearly could not have intended 
to imply the occupancy of the same region by forms the dis- 
parities of which are only to be accounted for on the ground 
of geographical variation, i.e., variation dependent on difference 
of locality. 
As a matter of fact, clarkii appears never to have been found 
in the interior except in fall or winter in Mexico, where, as is 
well known, birds may, in the dispersion attendant on migration, 
cross from the Pacific to the Atlantic side and yet be wholly 
wanting in the interior regions to the northward. 
On the other hand, all the specimens I have seen from the 
interior, i.e., between the Rocky Mountains and the Sierras, 
were typical examples of the large straight-billed form, occiden- 
talism and during the breeding season, typical occidentalis may be 
confined to the interior. Of the breeding range of clarkii 
nothing is positively known- The fact that the two forms are 
