Cory—The Genus Rhynchocylus. 221 
Range: Northeastern Peru (Ucayali; Exberos; Pebas, Nauta; Upper 
Ucayali; Yurimaguas); southeastern Peru (Cosnipata); eastern Ecuador 
(Napo); northwestern Brazil (Teffe, upper Amazon). 
Rhynchocyclus poliocephalus sclateri Hellmayr. 
Rhynchocyclus poliocephalus sclateri Hellmayr, Verh. zool.-bot. Gesell. 
Wien, lit, 1906, p. 207 (Barra de Rio Negro, N. Brazil Manaos). 
Rhynchocyclus poliocephalus (nom. nud.) Pelzeln, Orn. Bras., 1869, p. 110 
(Barra de Rio Negro; Maribitanas and Bahia). 
Rhynchocyclus megacephalus (nec Tyrannula megacephala Swainson) 
Sclater, Cat. Bds. Brit. Mus., XIV, 1888, p. 170 (Para, Brazil; De- 
merara, Merume Mts. and Carimang, British Guiana). 
Range: Northern Brazil (Rio Negro and Rio Madeira and eastward in 
Amazon region; Rio Tapajoz; Rio Tocantins; Rio Jamunda, etc., to Para); 
eastern Brazil (Bahia);! eastern Venezuela (Lower Orinoco and Caura 
River) ;? British Guiana; French Guiana; Dutch Guiana. 
This form is similar to R. p. poliocephalus from Peru, but differs in its 
larger size and somewhat smaller bill; by its whitish gray, instead of olive 
yellowish throat; grayish fore-neck (only slightly washed with olive yellow- 
ish), and paler yellowish under parts. Wing (type ex. by Hellmayr) 5714; 
tail53mm. The average wing measurements of 4 malesamd 5femalesfrom 
Oyapoc and Nana River, Cayenne, in the Carnegie Museum, males—wing 
55; females—wing 54 mm. 
Rhynchocyclus poliocephalus klagesi (Ridgway). 
Rhynchocyclus klagesi Ridgway, Proc. Biol. Soc. Wash., XIX, 1906, p. 
115 (Maripa, Venezuela). 
Range: Upper Orinoco River, Venezuela (Maripa and foot of Mt. Duida); 
§. E. Colombia (La Morelia and Florencia).$ 
This form is obviously closely related to R. p. sclateri, but differs in its 
brighter yellowish belly and in its yellowish-olive tinged breast and throat. 
Size about that of R. p. sclateri. The single specimen from the foot of Mt. 
Duida, 8. Venezuela, has the crown much darker (dusky slate color) than 
any specimen I have seen of either sclateri or klagesi, but otherwise agrees 
with klagest. 
Rhynchocyclus grisescens Chubb. 
Rhynchocyclus grisescens Chubb, Ibis, 1910, p. 588 (Sapucay, Paraguay). 
Range: Southeastern Paraguay (Sapucay). 
‘ 1Hellmayr (Novit. Zool., XVII, 1910, p. 298, footnote) has examined the specimen in 
the British Museum recorded by Sclater, Cat. Bds. Brit. Mus. XIV, 1888, p. 170, as speci- 
mens “a” “ Brazil’? under megacephalus, and learned that it came from Bahia and that it 
proves to be this form. 
2 According to Hellmayr (Novit. Zool., XVII, 1910, p. 298, footnote) specimens recorded 
by Berlepsch & Hartert from La Pricion, Caura River, Venezuela, as this form, prove to be 
a form of sulphurescens. If so, they are probably assimilis, which also occurs in that region. 
3Specimens in American Museum of Natural History. 
