( as) 
No. 1010. @ pull., Maruins, 13. vii, 1908. 
[No. 1451. ? imm., Borba, 7. xii. 1906.—Wing 88 ; tail 65; bill 14} mm. | 
In addition to the above, I have before me Natterer’s series, consisting of 
twelve specimens, kindly lent by the authorities of the Vienna Museum ; the four 
examples obtained by Mr. Hoffmanns at Humaytha; three skins from the Upper 
Orinoco (Munduapo, Nericagua); two from the Caura Valley, six from British 
Guiana (S. ¢. olivaceus); one each from Cayenne and Surinam, and five from Prata, 
Para (S. ¢. wallacii). The study of this large material revealed the fact that, 
notwithstanding a certain amount of individual variation, three distinct races are 
recognizable. Single specimens are not always distinguishable, yet it cannot 
be denied that the slight colour differences are connected with geographical 
distribution, 
(a) S. t. amazonum (Scl.). 
Hab. Peru: Chamicuros (Hauxwell, Bartlett), Yurimaguas (Stolzmann), 
- Soriano (Jelski), La Gloria (Kalinowski), Cosnipata (Whitely), etc. W. Brazil: 
Villa Maria, Engenho do Gama (Rio Guaporé), Mattogrosso (Natterer) ; Rio 
Madeira: Humaytha (Hoffmanns), Borba (Natterer), Allianca, Calama, Maruins 
(Hoffmanns); Rio Xié and Marabitanas, upper Rio Negro (Natterer), Eastern 
Ecuador: Sarayagu (Buckley). Venezuela, Upper Orinoco: Munduapo, Nericagua 
(Cherrie). 
Specimens from Sarayacu, Orinoco, and Rio Negro have, as a rule, the back 
brownish olive; the cap more or less tinged with cinnamomeous ; the throat and 
foreneck conspicuously washed with rufescent brownish ; and the remainder of the 
under parts dark greenish olive. The series from the Rio Madeira and its headwaters 
(Engenho do Gama, Villa Maria) are generally less brownish, more greenish olive 
on the upper parts, and the belly is slightly paler, more greyish olive ; but there 
are so many exceptions that I do not venture to separate them, inasmuch as I have 
no topotypical Peruvian material for comparison. Several examples from Humaytha 
and Calama show very little rafescent admixture on the pileum, and closely 
approach S, ¢. wallacit. : 
Immature birds have the outer aspect of the quills decidedly rufous brown, 
while in adult ones these edges are olive-brown, or very faintly tinged with 
russet. 
() 8. t. wallacit (Scl. & Salv.). 
Hab. N.B. Brazil: Pard (Wallace, Snethlage), Prata (Hoffmanns). French 
Guiana : Saint-Jean-du-Maroni (Le Moult; Mus. Munich). Surinam : near Para- 
maribo (Chunkoo ; Tring Museum). 
Five topotypes from near Para differ from the preceding form by purer green 
back, with very little, if any, rufescent tinge on the crown; paler, more greyish 
green belly; and by having the throat but slightly, if at all, shaded with brownish, 
Two birds from Cayenne and Surinam are in every respect typical. As stated above, 
some specimens from the Madeira are hardly different from wadllacit. 
(c) 8. t. olivaceus Ridgw. 
Scotothorus olivaceus Ridgway, Proc. Biol. Soc. Wash. xix. p. 118 (1906.—Rio Mato, Caura, Vene- 
zuela). 
Hab. Eastern Venezuela, Caura Valley: Mato R. (Klages), Nicare, La Pricion 
(André). British Guiana: Bartica Grove, Camacusa, R. Carimang, Roraima 
(H. Whitely, jr.). 
