14 TYRANNIDA. 
were described by Mr. Sclater under this name. The species was soon after found by 
us in the forests of the basin of the Rio de la Pasion, in northern Vera Paz, and it has 
since been traced to Tehuantepec, Tabasco, and British Honduras. It occurs again on 
the banks of the San Juan del Norte river, in Nicaragua, and on the line of the Panama 
Railway. Mr. Zeledon includes its name in his list of Costa Rica birds, but has not 
yet stated in what part of that country it is found’, The bird from the mainland of 
South America has been separated by Mr. Lawrence as 7. superciliaris on the ground 
of the under surface being rather whiter, and the white lores extending further over the 
eye'!, These differences are indeed slight, and hardly of specific value in our opinion. 
ONCOSTOMA. 
Oncostoma, Scl. Ibis, 1862, p. 12; Cat. Am. Birds, p. 208; Cat. Birds Brit. Mus. xiv. p. 76. 
Only two species are known of this curious form——-one from Southern Mexico and 
Central America, as far south as the Volcan de Chiriqui in the State of Panama, the 
other peculiar to the isthmus itself along the line of railway. 
The two species of this genus are olive-green above, greyish below, with the abdomen 
yellow, and thus resemble such members of the genus Todirostrum as T. schistaceiceps. 
But Oncostoma has several important differences. The bill is strongly arched, the 
culmen still more so, giving the bill a very different outline from that of Todirostrum, 
which is flat, and the culmen nearly straight; the tail is composed of narrow feathers, 
but is not nearly so rounded; the proportions of tail, wings, and tarsi are much as in 
Todirostrum. 
1. Oncostoma cinereigulare. 
Todirostrum cinereigulare, Scl. P. Z. 8. 1856, p. 295"; 1859, p. 884°. 
Oncostoma cinereigulare, Scl. Cat. Am. B. p. 208, t. 18. f. 1°; Cat. Birds Brit. Mus. xiv. p. 77‘; 
Salv. Ibis, 1866, p. 194°; P. Z.S. 1870, p. 196°; Lawr. Ann. Lyc. N. Y. ix. p. 1117; 
Bull. U. 8. Nat. Mus. no. 4, p. 26°; Sumichrast, Mem. Bost. Soc. N. H. i. p. 557°; Boucard, 
P. Z. 8. 1883, p. 447. 
Olivaceum ; capite summo vix saturatiore ; alis et cauda fusco-nigricantibus, extrorsum olivaceo limbatis ; capitis 
lateribus et gutture toto cinereis, hoc albicante striolato ; abdomine medio flavicante : rostro corneo ; pedibus 
pallide corylinis. Long. tota 4:0, al 2:0, caude 1°6, rostri a rictu 0-55, tarsi 0°6. (Descr. exempl. ex 
Coban, Guatemala. Mus. nostr.) 
@ mari similis. ; 
Hab. Mexico, Cordova (Sallé"), hot region of Vera Cruz (Swmichrast®), Teotalcingo 
and Playa Vicente (Boucard 2), Guichicovi, Cacoprieto, Tapana, Sta Efigenia (Sumi- 
chrast 1°), Tizimin® and Peto in Yucatan (Gaumer); Brirish Honpuras, Orange 
Walk (Gaumer) ; GuatemaLa, Coban ®, Teleman, Choctum, Savana grande, Volcan 
de Agua above San Diego, Retalhuleu (0. 8S. & F. D. G.); Costa Rica, Angostura 
(Carmiol’); Panama, Bugaba (Arcé *). 
