BIRDS OF NORTH AND MIDDLE AMERICA. 95 
Peripa, w. Ecuador; crit.)—Sanvin and Gopman, Biol. Centr.-Am., Aves, 
ii, 1892, 214, part (Lion Hill, Panama, and Chepo, Panama; Colombia; 
Ecuador; Peru; Guiana).—Banes, Proc. New Engl. Zool. Club, ii, 1900, 23 
(Loma del Leon, Panama).—Harrekt, Novit. Zool., ix, 1902, 612 (San Javier 
and Pambilér, n. w. Ecuador; crit.)—BrrurrscH and Hartert, Novit. 
Zool., ix, 1902, 76 (Munduapo, etc., Venezuela).—Hetiumayr, Novit. Zool., 
xii, 1905, 286 (near Pard, Brazil; crit.); xiii, 1906, 370 (Prata, near Par4); 
xiv, 1907, 32 (Obidos, Brazil; crit.) —Tuayer and Banas, Bull. Mus. Comp. 
Zool., xlvi, 1906, 217 (Sabana de Panama). 
[Cercomacra] tyrannina Prtzetn, Orn. Bras., iv, Abth., 1870, 419—ScuaTEeR and 
Satvin, Nom. Av. Neotr., 1873, 73, part—Swarrz, Hand-list, iii, 1901, 28, 
part (Panama; Colombia; Ecuador; Guiana; Amazonia). 
Hypocnemis schistacea (not of Sclater) Lawrences, Ann. Lyc. N. Y., vii, 1862, 325 
(Lion Hill, Panama). 
Disythamnus rufiventris Lawrence, Ann. Lyc. Nat. Hist. N. Y., vili, 1867, 181 
(Lion Hill, Panama; coll. G. N. Lawrence; =young male; see Salvin, 
Tbis, 1874, 316). 
CERCOMACRA TYRANNINA CREPERA (Bangs). 
DUSKY TYRANNINE ANTBIRD. 
Similar to C. ¢. tyrannina but adult male with coloration averaging 
much darker, the general color of upper parts blackish slate to slate- 
black, under parts slate color to blackish slate; adult female and 
young male not always distinguishable from those of C. t. tyrannina, 
but usually with color of upper parts darker and more brownish 
olive, the under parts decidedly deeper tawny.* 
Adult male.—Length (skins), 124-148 (137); wing, 60-67 (63.4); 
tail, 54.5-62.5 (57.2); culmen, 15-18 (16.6); tarsus, 21.5-24 (22.9); 
middle toe, 12.5-14 (13.5).° 
@ There is much variation in intensity of coloration among specimens from Costa 
Rica and northward. Asarule, specimens from the Caribbean slope are much darker 
than those from the Pacific side, and were the differences strictly geographical two 
well-marked forms could easily be made out; but unfortunately both slate-colored 
and blackish examples sometimes occur in the same locality, as in eastern Nicaragua 
(Rio Escondido), Honduras (Rio Blanco and San Pedro Sula), while extreme dark 
specimens come from Bebedero, northwestern Costa Rica, and light colored ones 
from British Honduras. A large majority of the specimens from southwestern Costa 
Rica are so light colored that they could almost be referred to true C. tyrannina; but 
touch darker ones occasionally occur there also. Specimens from Venezuela agree 
exactly with those from Bogoté and Panam4; but two adult males from Reyes and 
Mapiri, Bolivia, respectively, are quite as dark as the darkest examples of C’. ¢. 
crepera. On the whole, I consider our present understanding of this species, with 
reference to its geographic variations, far from satisfactory. 
6 Forty-four specimens, 
