716 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



g. Tail longer (averaging 48). 



Folioptila albiloris, adult female (p. 725) 

 Polioptila albiventris'!, adult female (p. 729) « 

 gg. Tail shorter (averaging 43) ..Polioptila bairdi, adult female (p. 726) 

 ee. A white superciliary stripe. 

 /. Larger (wing 45.5-47.5, tail 42-43.5). 



g. Much paler, the upper parts clear bluish gray or plumbeous, the 



under parts mostly white. .Polioptila bilineata, adult female ( p. 726) 



gg. Much darker, the upper parts slate color (nearly slate-black on 



' pileum), the under parts french gray or cinereous, white only on 



abdomen, hinder flanks, anal region, and under tail-coverts. 



(Highlands of Costa Eica. ). 



Polioptila superciliaris magna, adult female (p. 728) 

 ff. Smaller (wing 41.5-44, tail 36.5-40). (Coloration nearly as in P. s. 

 magna, but not quite so dark.) 



Folioptila superciliaris snpercilicris, adult female (p. 727) 

 dd. Gray of pileum darkening postero-laterally into blackish slate or nearly 

 black next to upper margin of auricular region, producing a conspicuous 

 dusky postocular patch. 

 e. Wing and tail shorter (wing 45.7, tail 45.1) ; less white on lateral rectrices. 

 Polioptila plumbiceps, adult female (extralimital) ^ 

 ee. AVing and tail longer (wing averaging 46.5, tail 48.7); more white on lat- 

 eral rectrices Polioptila leucogastra, adult female (extralimital) « 



bb. Outermost rectrix with much less than terminal fourth white. 

 c. Outermost rectrix with outer web wholly white, except basal third (more or 

 less); paler, the gray of upper parts bluish slate-gray or plumbeous, the 

 under parts grayish white or very pale gray. (Southern Texas to southern 



California, etc., and northern Mexico.) Folioptila plumbea*' (p. 731) 



cc. Outermost rectrix, with outer web, merely edged with white; darker, the 

 gray of upper parts deep slate-gray or slate color, the under parts light gray . 

 (Coast district of California and northern Lower California.) 



Polioptila californica'' (p. 734) 



aa. Tail very much graduated, the lateral rectrices only about half as long as middle 



pair. (Cuba.) Polioptila lembeyei « (p. 735) 



POLIOPTILA C^RULEA CiERULEA (Linnaeus). 

 BLTJE-GEAY GNATCATCHER. 



Adult male. — Pileum and hindneck plain bluish gray or grayish 

 blue/ the back, scapular.s, rump, and lesser vs'ing-coverts slightly 



« I can not distinguish the supposed female of F. alhirenfris from that of P. albilorln, 

 both coloration and dimensions appearing quite the same. The only specimen 

 examined is from Progreso, Yucatan, from which locality all males examined are 

 P. albiventris; but it is not impossible the specimen in question may in reality be an 

 example of P. albiloris which has straggled from its usual habitat. 



i See footnote * on p. 714. 



«See footnote " on p. 714. 



''Adult males of these two species have the pileum glossy blue-black, as in P. 

 nigriceps, P. albiventris, etc. 



« The adult male (adult female also?) of this species has a curved black line bor- 

 dering upper and posterior margin of the auricular region. 



/The color is not nearly approximated by any in the author's Nomenclature of 

 Colors; it is intermediate between plumbeous and azure blue, as there represented. 



