490 



BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



(?) Myiobius xanthopyyius (not I'lalyrhyncluis xunthopyyus Spix) Sclater and 

 Salvin, Proc. Zool. Soc. Lond., 186G, 189 (Ucayali, e. Peru). — Taczanowski, 

 Proc. Zool. Soc. Lond., 1874, 537 (centr. Peru). 



MYIOBIUS XANTHOPYGUS SULPHUREIPYGIUS (^Sclater). 

 SULPHUR-RUMPED MYIOBIUS. 



Adult male. — Above deep greenish olive, the occiput with a partially 

 concealed patch of bright canary or lemon yellow (rarely more orange- 

 3^ellow) ; wings dark sooty brown or dusky, the remigeo with brownish 

 edgings; rump primrose or pale canary yellow; upper tail-coverts and 

 tail black or brownish black; chin and throat pale grayish yellow; 

 chest and sides light tawny-brown or ^"ellowish cinnamon; median 

 portion of breast, abdomen, flanks, and anal region primrose yellow or 

 light canary yellow, the flanks tinged with the color of sides; under 

 tail-coverts pale yellowish, sometimes intermixed wath pale cinnamon- 

 brownish, usually with darker U or V-shaped lines of brown or dusky; 

 maxilla brownish black, mandible whitish (in dried skins) tipped with 

 dusky; iris brown; legs and feet horn brownish (in dried skins); 

 length (skins), 112-131 (121); whig, 56-69 (65.3); tail, 49-58.5 (53.7); 

 exposed culmen, 10.5-12.5 (11.6); tarsus, 17-19 (18.2); middle toe, 

 9.5-10.5 (9.9). « 



Adult female. — Similar to the adult male, but usually ^ without any 

 yellow on occiput; length (skins), 110-126 (118); wing, 58.5-67.5 

 (62.4); tail, 49-5G.5 (51.9); exposed culmen, 10.5-12.5 (11.5); 

 tarsus, 16-18 (16.6); middle toe, 8.5-10 (9.3).'-- 



a Sixteen specimens. 



b Twenty-one out of twenty-four specimens sexed as females have no trace -of yellow 

 on top of head, and one more has merely a trace, 

 c Fourteen specimens. 



It is not improbable that a satisfactory series of specimens may show the desirability 

 of separating the birds of Panama, Costa Rica, Nicaragua, and southern Honduras from 



