BIRDS COLLECTED IN PA RAO IJA Y— OBERHOLSER. 129 



mentalw, according toTeniniinck'.s orig-i rial plate and description, with 

 which the above mentioned Panigua^' specimen perfectly agr(H;.s, is 

 uniform dull gra3ash olive green on all the middle and posterior upper 

 parts, this color being trenchantly defined against the pliuiibeous of 

 head and cervix; the throat is grayish white, giving way rather 

 a))ruptly to the clear naples 3^ellow of breast and a})domen. But 

 Di/xlf/tdinniis oUvaceus is apparent!}^ quite a distinct species, the male 

 differing from that of D. mentalw in being usually quite uniform 

 plumbeous above, and though sometimes appreciably tinged with olive, 

 principally on the rump, never olive green; the lower surface poste- 

 rior to the throat is never clear yellow, but generally white medially, 

 much shaded with slate gray laterally, and on flanks and crissum tinged 

 with pale brownish, ochraceous, or yellowish. The same large series 

 which Dr. Allen studied has ])een examined in the present connection; 

 and a considerable number of additional specimens in the United States 

 National Museum, principally from Colombia and Central America, 

 have thrown light upon the questions involved. Two forms of 

 D. ollvacevs: are readily recognizable, D. oUvaceus olimccvs from Peru, 

 Bolivia and western Brazil, and D. olivaceus semicinerens from Colom- 

 bia and Central America. While it is true that there are absolutely 

 no valid characters by which the males of these two forms can be 

 separated, there is no difficulty at all in distinguishing the females, for 

 those of semicinereus are very much darker both above and below, 

 specimens from Colombia (Bogota) being extreme in this particidar. 

 With regard to the proper names for these two forms there is, unfor- 

 tunately, some room for question. The point to be determined is the 

 identity of Tschudi's name oUvaceus, which from plate and description 

 might apply to either the Brazilian or Central American bird. The 

 present separation of ol/'vaceus and senucinei'eus is based on comparison 

 of specimens from Matto Grosso, Brazil, which are considered to 

 represent oUvaceus, with examples from Bogota, the type locality of 

 semicinereus:, while none from Ecuador, Peru, or Bolivia have been 

 available. Should Peruvian specimens prove olivaceus identical with 

 semicinereus, the latter would, of course, become a synonjnn, and 

 another subspecific name would be necessary for the bird of west- 

 ern Brazil, which undoubtedly would be affi/nis Pelzeln.^ Although 

 strongly inclined to the belief that this will some day have to be 

 done, we refrain from making such a change until absolute proof of 

 the necessity be ol)tained. 



THAMNOPHILUS CiERULESCENS Vieillot. 

 TlKimuxiphilux c:rrulesce)ij< Vieillot, Nouv. Diet. d'Hist. Nat., Ill, ISKi, j). 311. 

 A single adult male in perfect plumage is apparently typical. "'Iris 



br 



•own. 



'Orn. Bras., 1869, pp. 80, 149. 

 Proc. N. M. vol. XXV— 02 9 



