BIRDS OF NORTH AND MIDDLE AMERICA. 95 



Peripa, w. Ecuador; crit.). — Salvin and Godman, Biol. Centr.-Am., Aves, 

 ii, 1892, 214, part (Lion Hill, Panama, and Chepo, Panama; Colombia; 

 Ecuador; Peru; Guiana).— Bangs, Proc. New Engl. Zool. Club, ii, 1900, 23 

 (Loma del Leon, Panama).— Hartert, Novit. Zool., ix, 1902, 612 (San Javier 

 and Pambilar, n. w. Ecuador; crit.). — Berlepsch and Hartert, Novit. 

 Zool., ix, 1902, 76 (Munduapo, etc., Venezuela). — Hellmayr, Novit. Zool., 

 xii, 1905, 286 (near Para, Brazil; crit.); xiii, 1906, 370 (Prata, near Para); 

 xiv, 1907, 32 (Obidos, Brazil; crit.). — Thayer and Bangs, Bull. Mus. Comp. 

 Zool., xlvi, 1906, 217 (Sabana de Panama). 



[Cercomacra] tyrannina Pelzeln, Orn. Bras., iv, Abth., 1870, 419.— Sclater and 

 Salvin, Nom. Av. Neotr., 1873, 73, part.— Sharpe, Hand-list, iii, 1901, 28, 

 part (Panama; Colombia; Ecuador; Guiana; Amazonia). 



Hypocnemis schistacea (not of Sclater) Lawrence, Ann. Lye. N. Y., vii, 1862, 325 

 (Lion Hill, Panama). 



Disythamnus rufiventris Lawrence, Ann. Lye. Nat. Hist. N. Y., viii, 1867, 131 

 (Lion Hill, Panama; coll. G. N. Lawrence; = young male; see Salvin, 

 Ibis, 1874, 316). 



CERCOMACRA TYRANNINA CREPERA (Bangs). 



DUSKY TYRANNINE ANTBIRD. 



Similar to C. t. tyrannina but adult male with coloration averagino; 

 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).^ 



a There is much variation in intensity of coloration among specimens from Costa 

 Rica and northward. As a rule, 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 

 much darker ones occasionally occur there also. Specimens from Venezuela agree 

 exactly with those from Bogota and Panamd; but two adult males from Reyes and 

 Mapiri, Bolivia, respectively, are quite as dark as the darkest examples of C. t. 

 crepera. On the whole, I consider our present understanding of this species, with 

 reference to its geographic variations, far from satisfactory. 



b Forty-four specimens. 



