62 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
Range.—Isthmus of Panam& to Cayenne and Amazon Valley. 
(At least four species.)¢ 
KEY TO THE SPECIES OF MYRMOTHERULA. 
a. Under parts white, streaked with black. (Panam4 to Guiana and western Ecuad6ér.) 
Myrmotherula surinamensis, adult male (p. 62). 
aa. Under parts neither white nor streaked with black. 
b. Under parts buffy, deepening into tawny on chest . 
Myrmotherula surinamensis, adult female (p. 62). 
bb. Under parts of body pale straw or primrose yellow. 
c. Pileum narrowly streaked with pale yellow or yellowish white; throat white. 
(Panamé4 to Cayenne and Peru).Myrmotherula pygmea, adult male (p. 64). 
cc. Pileum streaked with pale rufous or tawny; throat buff or pale tawny. 
Myrmotherula pygmea, adult female (p. 64). 
MYRMOTHERULA SURINAMENSIS (Gmelin). 
SURINAM ANTWREN. 
Adult male-—Pileum, hindneck, back, and scapulars black, nar- 
rowly streaked with white, the feathers of back extensively white 
basally; rump plain gray (nearly no. 6), much paler posteriorly; 
upper tail-coverts dusky, indistinctly margined terminally with 
whitish; tail black, the rectrices tipped with white and edged on 
middle portion with the same; wings black, the middle and greater 
coverts broadly tipped with white (forming two very conspicuous 
bands across wing), the remiges edged (except on basal portion of 
distal secondaries and proximal primaries) with white; under parts 
white, the throat narrowly, the chest, breast, sides, and flanks 
broadly, streaked with black; under wing-coverts and broad edgings 
to inner webs of primaries white; maxilla dull black, mandible dull 
whitish (in dried skins); legs and feet pale yellowish gray (in dried 
skins); length (skins), 90-107 (96); wing, 49.5-52.5 (51); tail, 
26-28.5 (26.9); culmen, 14-15.5 (15); tarsus, 16.5-18.5 (17.2); 
middle toe, 9.5-10.5 (9.9).2 
Adult female—Pileum bright tawny, the occiput and posterior 
part of crown streaked with black, the hindneck more buffy and with 
black streaks broader; back and scapulars black, streaked with 
@ The following species, referred to Myrmotherula by Dr. Sclater, I have not seen 
and therefore have no very clear idea of the limits of the group: M. guttata (Vieillot), 
M. spodionota Sclater and Salvin, M. atrogularis Taczanowski, M. hematonota (Sclater) 
M. pyrrhonota Sclater and Salvin, M. erythrura Sclater, M. erythronota (Hartlaub), 
M. hauxwelli (Sclater), M. longipennis Pelzeln, M. brevicauda (Swainson), M. 
urosticta (Sclater), M. inornaia Salvin, M. unicolor (Ménétriés), M. longicauda Ber- 
lepsch and Stolzmann, WM. sororia Berlepsch and Stolamann, M. guayabambex Sharpe, 
M. lafresnayeana (D’Orbigny), M. viduata Hartert, M. sanctemartx Allen, M. behni 
Berlepsch and Leverkuhn, and M. boliviana Berlepsch. It is not unlikely that 
when all these species can be critically compared a further subdivision of the genus 
may be required. 
b Four specimens. 
