HenSHaW oft P. occidentalis and P. clarkii . 215 
instructive series of these birds, I propose here to briefly discuss 
the question with a view to definitely settling, if possible, the 
relationship of the two. The series alluded to consisted of eleven 
beautifully prepared specimens in the collection of Mr. D. S. 
Bryant of Oakland, California, to whose kindness I am indebted 
for the opportunity of studying the series, and were all shot the 
same spring in San Francisco Harbor by Walter Bryant. 
The characters which served originally to distinguish the two 
birds are as follows :* — 
Occidentalism'. Size large — wing 8| inches; bill 3 inches: tarsus 3 
inches; bill straight, dusky or nearly black, except cutting edges 
near end where it is yellow; line from eye to base of upper man- 
dible gray. 
Clarkii: Size smaller — wing 73 inches; bill 23 inches, tarsus 2I inches; 
bill with both upper and lower mandibles slightly recurved; color 
yellow except the edge of upper mandible, which is black; line 
from eye to base of upper mandible white. 
Assuming that the above characters are all that can be brought 
forward to distinguish the two birds — and I can find no others — 
the simple question is Do the two maintain their respective char- 
acters so as to be always distinguishable or do specimens occur 
having the supposed distinctive features variously intermingled 
and varying to a greater or less extent? In other words, can 
intergradation between the two birds be proven? I answer in 
the affirmative and for proof refer the reader to the annexed table. 
A glance at the table will reveal the fact that the several 
characters assigned the two birds are variously interchanged, 
some of the larger individuals referable to occidentalis having 
in addition to certain of the characters of that form peculiarities 
belonging to clarkii ; others possess the small size of clarkii 
but with the form and color of bill and loral space of occidentalis. 
Therefore no distinct line can be drawn between the two, and 
it occasionally becomes a matter of nice judgment to decide to 
which of the two forms a given specimen should be referred. 
The color of the loral spaces varies from being indistinguishable 
from the color of the head (greenish-black) to a pure white ; 
* See Birds North America, 1858,^.894, 895. 
f It is noticeable that the series examined by the original describer contained one 
specimen which, though doubtfully referred to occidentalis , was remarked to possess 
certain of the characters distinguishing clarkii. 
