Vol. XVI-] Birtwell, An Example of Aptosochromatism. 313 



1899 J 



Dendroica tigrina. Cape May Warbler. — Mr. Link has seen seven 

 examples of this species, some of which were taken in the Pittsburgh 

 City limits. I examined two specimens in his collection taken there. 

 " A specimen taken in Allegheny Co., Aug. 28, 1S96." Atkinson. 



Dendroica cserulea. Cerulean Warbler. — So far from this being a 

 very rare bird, as in eastern Pennsylvania, it may be said to be numerous 

 in the southwestern part of the State, where it breeds. I found it breeding 

 in the vicinity of Pittsburgh, Beaver, and Ligonier, Westmoreland Co. 

 It does not breed in the mountain districts of that County, however, 

 none being seen at Laughlintown. It is a very loud and persistent 

 songster. 



Geothlypis agilis. Connecticut Warbler. — A male specimen was 

 taken by Mr. Link, June 4, 1894. Another now in the Carnegie Museum 

 was shot at Leetsdale, Allegheny Co., May 24, 189S, a female. 



Geothlypis Philadelphia. Mourning Warbler. — I found this bird 

 breeding near Laughlintown ; several pairs being noted on Laurel Ridge. 



Geothlypis trichas. Maryland Yellow-throat. — The great scar- 

 city of this bird in Allegheny and Beaver Counties %vas a surprise to me. 

 Only two were noted. A few were found breeding at Laughlintown. 



Sylvania mitrata. Hooded Warbler.— Two seen in May at Beaver. 

 One singing male noted near Laughlintown in June. A specimen was 

 taken at Leetsdale in May, 1S98. They appear to be rare. 



Anthus pensilvanicus. American Pipit. —The late spring and early 

 August appearances of this bird in Beaver County noted by me suggest 

 that it may be found breeding in the northwestern counties of Pennsyl- 



vania. 



Thryothorus bewickii. Bewick's Wren. — In 1894 I discovered this 

 bird breeding on the top of Tuscarora Mountain, Fulton County. One 

 specimen was taken at Beaver, April 27, 189S. Two were recorded by me 

 near Round Island, May 27, 1896. 



Cistothorus stellaris. Short-billed Marsh Wren. — "One cap- 

 tured in Allegheny Co., May 4, 1894." Atkinson. 



AN EXAMPLE OF APTOSOCHROMATISM, AS INFLU- 

 ENCED BY DIET, IN MEGASCOPS AS/O. 



BY FRANCIS J. BIRTWELL. 



In the following pages I shall attempt to detail an account 

 of a very remarkable example of color change without moult or 

 feather loss (Aptosochromatism); but unfortunately the results 



