NO. 9 BIRDS OF ISLA COIBA, PANAMA—WETMORE 99 
heavily with dark greenish olive, the streaks becoming narrower on 
lower breast until they are reduced to lines on the upper abdomen 
and on its sides ; center of abdomen white; sides dark greenish olive ; 
flanks and under tail coverts between cartridge buff and cream-buff, 
streaked indefinitely with Chaetura drab ; edge of wing citron yellow ; 
outer under wing coverts primrose yellow; inner series and axillars 
cream-buff. Bill black; tarsus and toes fuscous-black (from dried 
skin). 
Measurements.—Males (6 specimens), wing 84.6-90.5 (87.8), tail 
760.4-78.7 (77.6), culmen from base 17.3-18.8 (18.3), tarsus 23.4-24.0 
(23.6) mm. Females (7 specimens), wing 84.3-88.8 (86.8), tail 74.5- 
79.8 (77.3), culmen from base 17.7-19.0 (18.4), tarsus 22.0-24.2 
(23.0) mm. 
Type, male, wing 90.1, tail 87.6, culmen from base 17.5, tarsus 
23.4 mm. 
Range.—Isla Coiba and Isla Rancheria, off the Pacific coast of 
Veraguas, Panama. 
Remarks.—The darker coloration sets this form apart as con- 
spicuously distinct from the other known subspecies. The green hues 
have a definitely dark-gray cast, and the streaking on the under sur- 
face is heavy, even more so than in S. a. furax of western Chiriqui 
and southwestern Costa Rica. 
The name is taken from the Greek oxozwos, dark, obscure, referring 
to the color. 
TIARIS OLIVACEA (Linnaeus): Yellow-faced Grassquit, Yerbero 
Emberiza olivacea LINNAEUS, Systema naturae, ed. 12, vol. 1, 1766, p. 300. 
( Hispaniola. ) 
The grassquit was common along the borders of the pastures and 
at the edge of the forest, congregating especially where tall grasses 
bore ripening seeds. They feed by balancing on the grass heads as 
these sway and bend beneath their slight weight. At headquarters 
dozens came to feed about the mill that hulled the rice, and in the 
remote work camps, where rice was pounded by hand, the grassquits 
gleaned the fallen grain about the kitchens. They were completely 
tame, and often came hopping about the feet of men sitting on the 
benches at guard headquarters. Fully grown young were common, 
and on January 14 adults were mating. 
The dark color of these birds was noticeable even in life, the 
differences from the mainland group being detailed in the following 
description. 
