624 Annals of the Carnegie Museum. 



which exhibit a phase of plumage which I believe has not hitherto 

 been described. 



The entire plumage is darker than in mature birds, the pileum and 

 upper parts being of a darker, richer brown ; the portion of the throat 

 which is black in adult birds, is white, each feather tipped with black, 

 and in two specimens with submarginal spots of light brown ; the 

 whole chest is slaty-black, each feather edged with the color of the 

 upper parts ; the remainder of the lower parts about the same as in 

 the adult. 



This species is confined to the southwestern Pacific coast region, 

 from the Rio Grande de Tarcoles southward, and from sea-level up to 

 about 1,500 feet. It is quite abundant in the Pirns Valley and very 

 common in the lowlands of the Terraba region. It inhabits the heavy 

 dark forest, is strictly terrestrial, and feeds a great deal upon the 

 common foraging ants. The males have a very musical note, which 

 is heard more or less the year round, but more commonly during the 

 breeding season. It resembles very closely the same notes described 

 under Mynnelastes exsul, ' except that it is louder and clearer, and 

 never consists of less than four notes, often six or seven. The males 

 (but never the female) are easily decoyed by imitating this note, 

 coming close up to the person calling, if he remains perfectly still. 

 The females are much shyer than the males and are very difficult to 

 secure. 



360. Formicarius umbrosus Ridgway. 



Formicarius hoffmanni Boucard, P. Z. S., 1878, 62 (San Carlos). — Zeledon, 

 An. Mus. Nac. de C. R., I, 1887, 115, patt (Jimenez and Pacuare). — Salvin 

 and Godman, Biol. Centr.-Am.. Aves, II, 1892, 234, part (Costa Rican refer- 

 ences). 



Formicarius umbrosus Ridgway, Proc. U. S. Nat. Mus., XVI, 1893, 681 (Tala- 

 manca, Costa Rica [J. Cooper]; Jimenez [Verrillj). — Underwood, Ibis, 

 1896, 441 (Miravalles). 



U. S. Nat. Museum : Rio Matina (Cherrie), Jimenez (Alfaro), 



Bonilla (Ridgway). 

 Bangs Collection : La Vijagua and Jimenez (Underwood). 

 Carnegie Museum : Guapiles and Guacimo (Carriker & Crawford) ; 



Guapiles, Cuabre, Rio Sicsola, Miravalles, and Bagaces (Carriker). 



Nineteen skins. 



This is the common Formicarius of the Caribbean lowlands and the 

 Pacific lowlands of the northwestern portion of Costa Rica, from the 



