: 
PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 413 
difference prove constant, one of the forms requires a new name; and 
L. leucothorax having been based upon specimens from Tucurrique, the 
central part of Costa Rica, it follows that the black-rumped one is the 
one to be named. Accordingly, in view of its probable distinctness, I 
propose for it the name L. melanopygius. 
There appears to be little difference in dimensions, the three speci- 
mens measuring as follows: 
| Sat ' 
‘pill from ae Middle 
Specimen. | Wing. | Tail. | Culmen. | nostell +06 
MAEM IERIE TIS foot Se oe a oo at wn wlescie's'eaena Se peise 4.00 | 3.70 . 95 . 60 70 - 50 
RNG eae ATICOSUUTS W-- 20 - cesta eres emceswcee 4.15 | 3.70 .90 .59 Pui) 55 
RUBE EUR 2c oc ate aeons lane se | 4.00 | 8.70 . 85 52 .70 | . 50 
8. Empidonazx atriceps Salvin. 
The single specimen of this species may be described as follows: 
Sp. cH.—Adult (No. 91829, Pirris, Costa Rica, 1882; J. Cooper): 
Pileum and nape uniform sooty black, somewhat paler on the forehead; 
back and scapulars dark sooty olive, or olive-sepia, the rump similar, 
but paler; tail uniform dull black; wings black, the middle coverts 
broadly tipped with the color of the back, the greater coverts broadly 
‘tipped with lighter brown, and tertials edged with the same. Orbital 
ring, chin, and throat, light grayish yellow; sides of head dull oliva- 
ceous, much the same tint as the rump; jugulum and breast raw-umber 
brown, becoming more ochraceous posteriorly, the abdomen and cris- 
sum, also axillars and lining of wing, pale dull yellowish buff; maxilla 
black, mandible whitish; legs and feet black. Wing 2.45; tail 2.25, 
deeply emarginated ; culmen .45, width of bill at base .22, tarsus .65, 
middle toe .35. 
It seems to me that this species has been wrongly placed in the genus 
Empidonax ; at any rate, the specimen under examination seems strictly 
congeneric with Mitrephanes aurantiiventris, with which it agrees very 
minutely in details of structure, although of smaller dimensions. 
9. Empidonax viridescens sp. noy. 
Sp. cH.— Adult (No. 91826, U. S. Nat. Mus., Cervantes, Costa Rica, 
1882; J. Cooper): Above uniform bright yellowish olive-green or oil- 
green, becoming less yellowish on rump; tail dull grayish, feathers 
edged with olive-green; wings grayish dusky, except lesser coverts, 
which are rich oil-green, like back, &c.; middle coverts broadly tipped 
with deep olive-buff, greater coverts broadly tipped with paler, more 
yellowish buff; tertials edged with pale greenish; orbital ring (appa- 
rently interrupted at and above anterior angle of the eye) yellowish 
white or pale sulphur-yellow; anterior lower parts light yellowish olive, 
becoming pure yellow on the abdomen, the crissum similar but paler; 
middle of throat tinged with or inclining to yellow ; edge of wing tinged 
with saffron-yellow. Maxilla deep black, mandible wholly whitish, in- 
