BIRDS OF NORTH AND MIDDLE AMERICA. 279 
KEY TO THE SPECIES AND SUBSPECIES OF SITTASOMUS. 
a. Pale band across inner web of remiges very sharply defined, very distinct on 
secondaries as well as on primaries, and in color distinctly yellowish. 
b. Tail and secondaries rufous-chestnut or deep cinnamon-rufous. 
c. Under parts olive-yellowish. (Southeastern Brazil, etc.) 
Sittasomus erithacus (extralimital).¢ 
cc. Under parts grayish olive or olive-grayish. 
d. Back mixed rusty and olive. 
e. More olivaceous, with much smaller bill: under wing-coverts and band 
across inner web of remiges deeper yellowish. (Southwestern Brazil, 
GUC. Ys seinkdawekcol cccaiee ss eee Ss Sittasomus chapadensis (extralimital). 
ee. More grayish, with much larger bill; under wing-coverts and band acrosa 
inner webs of remiges paler yellowish. (Upper Amazon Valley.) 
Sittasomus amazonus (extralimital).¢ 
dd. Back uniform russet brown. (Sittasomus sylvioides.) 
e. Smaller (male averaging, wing, 77.1; tail, 73.5; exposed culmen, 14 mm.). 
(Southeastern Mexico to Costa Rica.) 
Sittasomus sylvioides sylvioides (p. 280). 
ee. Larger (male averaging, wing, 84; tail, 77.5 or more; exposed culmen, 
15.4 or more). 
f. Tail and bill shorter (tail averaging 77.5, exposed culmen 15.4). (Pan- 
AMAs) Wd Lsee/se han wou sacs Aemwads Sittasomus sylvioides levis (p. 282). 
ff. Tail and bill longer (tail averaging 81, exposed culmen 16.5). (Western 
MexXiC0.) 3222.0 055%s sens Sittasomus sylvioides jaliscensis (p. 283). 
bb. Tail and secondaries clear tawny. (Western Ecuadér.) 
Sittasomus zequatorialis (extralimital).4 
aa. Pale band across inner web of remiges not sharply defined, very indistinct on 
secondaries, in color white or yellowish white. (Tobago.) 
Sittasomus griseus (extralimital).e¢ 
@ D{endrocolaptes] erithacus Lichtenstein, Abh. Kénigl. Akad. Wissensch. Berlin, 
for 1820-21 (1822), 259, 266, pl. 1, fig. 2 (Province of Sao Paulo, s. Brazil; coll. Berlin 
Mus.).—[Stttasomus] erythacus Bonaparte, Consp. Av., i, 1850, 209.—Sittasomus eri- 
thacus Lafresnaye, Rev. Zool., 1850, 589; Sclater, Cat. Birds Brit. Mus., xv, 1890, 
119; Ridgway, Proc. U. 8. Nat. Mus., xiv, 1891, 508 (monogr.).—Sittasomus sylviellus 
Temminck, Pl. Col., livr. 12, Sept. 27, 1823, text to pl. 72, fig. 1; Menegaux and 
Hellmayr, Mém. Soc. Hist. Nat. d’Autun, xix, 1906, 95 (Goyaz, Brazil; crit.).—Sit- 
tasomus sylviellus sylviellus Hellmayr, Novit. Zool., xv, 1908, 63 (Goyaz and Faz. 
Esperanga, Brazil).—Acanthurus microrhynchus Bertoni, Aves Nueves del Paraguay, 
1901, 72.—S[tttasomus] olivaceus Maximilian, Beitr. Naturg. Bras., iii, 1831, 1146. 
b Sittasomus chapadensis Ridgway, Proc. U. S. Nat. Mus., xiv, no. 877, Oct. 31, 
1891, 509 (Chapada, Matto Grosso, s. w. Brazil; coll. Am. Mus. Nat. Hist.); Mene- 
gaux and Hellmayr, Mém. Soc. Hist. Nat. d’Autun, xix, 1906, 95 (Chiquitos, Bolivia; 
crit.).—Sittasomus sylviellus chapadensis Hellmayr, Novit. Zool., xv, 1908, 63 (Rio 
Thesouras, Brazil; crit.). 
¢ Sittasomus amazonus Lafresnaye, Rev. et Mag. de Zool., 1850, 509; Ridgway, 
Proc. U. 8. Nat. Mus., xiv, 1891, 509 (monogr.); Menegaux and Hellmayr, Mém. 
Soc. Hist. Nat. d’Autun, xix, 1906, 96 (Yungas, Bolivia; up. Amazon).—Sittasomus 
olivaceus amazonus Hartert, Kat. Vogelsamml. Senckenb., 1891, 110 (Bolivia). 
4 Sittasomus xquatorialis Ridgway, Proc. U. 8. Nat. Mus., xiv, no. 877, Oct. 31, 
1891, 509 (Guayaquil, w. Ecuadér; coll. U. S. Nat. Mus.). 
e Sittasomus griseus Jardine, Ann. and Mag. N. H., xix, 1847, 82 (Tobago); Ridg- 
way, Proc, U. 8. Nat. Mus., xiv, 1891, 510 (monogr.). 
