80 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
summits of the tallest forest trees in the interior of the island. In- 
variably they were moving about among the twigs and leaves in 
unceasing activity in pursuit of tiny insects, often so high above the 
ground that I could barely detect their tiny forms. The slender body, 
with long, narrow tail held at an angle above the back, and their 
quick, nervous movements, mark them even when the gray and 
white plumage is not clearly seen. I found them in pairs, and near 
breeding at this season. January 21 one male was much excited by 
Fic. 11.—Tropical Gnatcatcher, Cazajején. 
my squeaking, and came to perch within a dozen feet of me while it 
sang repeatedly a series of high-pitched notes of the usual gnatcatcher 
quality, barely audible to my aging ears, mingled with beautifully 
clear, warbling phrases of much louder sound that would have graced 
the gifted song of a mockingbird. 
Darker coloration separates the birds of Coiba definitely from 
their mainland neighbors, as shown by the following description. 
POLIOPTILA PLUMBEA CINERICIA subsp. nov. 
Characters.—Similar to Polioptila plumbea bilineata (Bonaparte) ** 
but dorsal surface, including the wings, decidedly darker gray ; lower 
23 Polioptila bilineata Bonaparte, Conspectus generum avium, vol. 1, 1850, 
p. 316. (Cartagena, Colombia.) 
