Brewster on Certain Pol /opt i he. IOI 



ON THE AFFINITIES OF CERTAIN POLIOPTIL^S, 

 WITH A DESCRIPTION OF A NEW SPECIES. 



BY WILLIAM BREWSTER. 



In a collection of Arizona birds, elsewhere considered in die 

 present number of the Bulletin, is a small series of Gnatcatchers, 

 which brings to light some very interesting developments affecting 

 the relationship of certain members of the genus Polioptila. As 

 the matter seems of sufficient importance to merit special treat- 

 ment, I present it separately in the following paper : 



Folioptila plumbea. Baird. et melanura Lawr. 



It has been somewhere suggested that P. -plumbea might after 

 all be only a geographical race of P. ccernlca. but the specific 

 distinctness of the former from P. melanura seems never to have 

 been questioned.* The fact that their distribution was the same 

 has effectually precluded any suspicions of varietal affinity, and 

 the real secret, singularly enough, has eluded the few ornitholo- 

 gists who have paid any attention to the subject. 



But thanks to the exertions of Mr. Stephens, who it seems has 

 for some time suspected their identity. I now have before me a 

 perfect connecting series between the two supposed species. 



A brief consideration of rive of the specimens, all of which 

 were taken near Tucson during the spring of 1SS0. will present 

 the case as fully as is desirable. 



The first (No. 4980, author's collection) £, March 3. is typical of the 

 state known as P. plumbea, the black on the head being restricted to a 

 short stripe on each side of the crown, which, beginning nearly above 

 the anterior margin of the eye, extends backward to a short distance 

 behind it, and is bounded below by a superciliary line of ashy-white. 



In the second (No. 4982)0*, March 4. the black stripe broadens, en- 

 croaching on the superciliary line, and meeting its fellow across the 

 top of the head between the eyes, in a narrow but decided band of black, 

 but leaving the anterior portion of the forehead ashy. 



The third (No. 4983)0* > March 5, has the whole crown essentially black, 

 but traces of the superciliary line remain, and in addition to an ill-defined 

 frontal-band of ashy, there are occasional leathers of that color scattered 

 among the darker ones. 



* Cooper hinted such a suspicion (Birds of Cal., I, p. 38) but his suggestion has 

 been generally ignored. 



