HenSHAW oji P. occidcntalis a nd 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 75 inches ; bill 2^ inches, tarsus 2! 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 occidcntalis 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, p. 894, 895. 



t 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. 



