| eta | BANGS — COSTA RICAN BIRDS 27 
Characters — Of about the same size as true P. versicolor (Hartl.) of 
Colombia, but differing considerably in markings and color. The adult 
male of the new form has the barring below much more strongly pro- 
nounced, the dark bars wider and blacker, and the sides of head, neck 
and throat much brighter olive yellow. The adult female has the sides 
of head and throat much darker — more strongly olive yellow, and the 
whole under parts rather yellower. 
Remarks.— In Part IV of his great work Ridgway pointed out 
the differences shown by the Costa Rican form of P. versicolor, 
and although he did not give it a name, he has told me he was 
much tempted to do so. At that time he had but two specimens 
from Costa Rica before him — adults, male and female — both 
from my collection. Since then I have received from Underwood 
one more; an adult female, killed as were the others on Irazt, and 
I have not the slightest hesitation in giving the form, which is well 
marked, a name. he bird is very seldom taken by collectors, 
being either very rare or singularly hard to shoot. 
Myiobius xanthopygus aureatus subsp. nov. 
Type, from Divala, Chiriqui, Panama, 3 adult, no. 8036, coll. of E. A. 
and O. Bangs, collected April 21, 1900, by W. W. Brown, Jr. 
_ Characters.— Similar to Myiobius xanthopygus sulphurerpygius (Sclater) 
of southern Mexico, but slightly smaller; decidedly paler in color below — 
the tawny brown of chest and sides lighter, the yellow of belly clearer 
and usually brighter; under tail coverts pale yellow, usually, though not 
always, with U- or V-shaped brownish markings. (The under tail coverts 
in M. xanthopygus sulphureipygius are always light cinnamon-brown). 
From M. zanthopygus xanthopygus of eastern Brazil the new form differs 
in the olive of back being darker, and the under tail coverts being yellow, 
and from M. xanthopygus villosus of Colombia, Peru and Bolivia in less 
brownish color of back, paler chest and sides, and larger yellow belly patch. 
Measurements.— Adult male, type: wing, 63.5; tail, 53.; tarsus, 18.; 
exposed culmen, 11.5 mm. (Numerous other skins measured by me corre- 
spond so closely to the figures given by Ridgway on page 490, Part IV, 
Birds of North and Middle America, that I do not list them). 
Remarks.— Since Ridgway ' so clearly pointed out the characters 
that distinguish the Mexican and Central American forms of 
1 Birds of North and Middle America, Part IV, pp. 490-491, foot-note. 
