52 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



and Festa, Boll. Mus. Zool., etc., xv, no. 362, 1899, 27 (Vinces and Foreste 

 del Rio Peripa, w. Ecuador); no. 399, 7 (Laguna del Pita, Fanamd). — Thayer 

 and Bangs, Bull. Mus. Comi?. Zool., xlvi, 1906, 216 (Sabana de Panamd). 



[Thamnophilus] atrinucha Sharpe, Hand-list, iii, 1901, 14. 



[Thamnophilus] nxvius atrinucha Hellmayr, Abh. K. B. Akad. Wiss., ii. Kl., 

 xxii Bd., iii. Abth., 1905, 659 (crit.). 



Thamnophilus nxvius atrinucha Carriker, Ann. Carnegie Mus., vi, 1910, 602 

 (Caribbean lowlands and foothills, Costa Rica; crit.; habits; descr. nest and 

 eggs). 



ERIONOTUS PUNCTATUS GORGON.^ (Thayer and Bangs). 



GORGONA ISLAND ANTSHRIKE. 



Similar to E. p. atrinucha but adult male with forehead more 

 extensively grayish,'^ the adult female with lateral under parts paler 

 (nearly concolor with median portion). 



Gorgona Island, Bay of Panama. 



Adult male.— Length, (skins), 143-148 (146); wing, 70-75 (72.1); 

 tail, 57-61 (59); culmen, 18.5-20 (19.4); tarsus, 20-21 (20.5); middle 

 toe, 12.5-13 (12.7).'' 



Adult female.— Length (skins), 140-148 (144); wing, 68.5-72.5 

 (70.1); tail, 54.5-57.5 (56.1); cuhnen, 18.5-20 (19.1); tarsus, 21-21.5 

 (21.1); middle toe, 13-14 (13.4).«' 



Thamnophilus gorgonse Thayer and Bangs, Bull. Mus. Comp. Zool., xlvi, no. 5, 

 June, 1905, 95 (Gorgona Island, Bay of Panama; coll. E. A. and O. Bangs). 



Genus DYSITHAMNUS Cabanis. 



Dysithamnusc Cabanis, in Wiegmann's Archiv fiir Naturg., xiii, pt. i, 1847, 223. 

 (Type, Lanius guttulatMS Lichtenstein.) 



Dasythamnus (emendation) Burmeister, Syst. Ueb. Th. Bras., iii, 1856, 82. 



Silvestrius^ Bertoni, Aves Nuevas del Paraguay, 1901, 136. (Type, Thamno- 

 philus {Silvestrius) fiavescens Bertom= Myothera mentalis Temminck.) 



Small Formicariidse (length about 100-115 mm.) with bill much 

 shorter than head, tail less than three-fourths as long as wing and 

 slightly rounded, tarsus one-third as long as wing, and plainly colored 

 plumage (olive or olive-greenish above, becoming gray or slate colored 

 on head and neck, the pileum sometimes streaked or spotted mth 

 blackish, mostly whitish or yellowish below, sometimes with streaks 

 on throat and chest, females more brownish, with pileum rufescent. 



Bill much shorter than head, its width at frontal antiae slightly 

 greater than its depth at same point and equal to about half the dis- 

 tance from nostril to tip of maxilla; culmen distinctly but not 

 sharply ridged, nearly straight for most of its length, strongly and 

 rather abruptly decurved terminally, the tip of maxilla moderately 



c On comparison with a large series oi E. p. atrinucha I find that most of the char- 

 acters mentioned by Mr. Bangs do not hold. 

 & Four specimens. 



c8l}u>, hineinbegeben ; Ohjivog, Gebiisch. (Cabanis.) 

 <i Named for Dr. Felipe Silvestri. 



