ARBOREAL RICE RATS — ^HERSHKOVITZ 535 



Nat. Hist., ser. 9, vol. 19, p. 370, 1927 (Yurac Yacu, San Martfn, Peru, 



"mostly caught in house"); ser. 10, vol. 2, p. 262, 1928 (San Jer6nimo, Loreto, 



Peru). 

 Oecomys bicolor, Osgood, Field Mus. Nat. Hist., zool. ser., vol. 10, p. 161, 1914 



(Tambo Yacu, near Rioja, San Martfn, Peru). — Gyldenstolpe, Kungl. 



Svenska Vet.-Akad. Handl., vol. 11, p. 39, 1932 (characters; "type locality: 



South-western Ecuadoj, Guayaquil." — Tate, Zoologica, vol. 32, p. 66, 1947 



(Rancho Grande, Aragua, Venezuela, 1,100 meters). 

 Rhipidomys rosilla Thomas, Ann. Mag. Nat. Hist., ser. 7, voi. 14, p. 35, 1904 



(type locality, La Uni6n, lower Rio Caura, Rio Orinoco, Bolivar, Venezuela). 

 [Oryzomys (CEcomys)] rosilla, Thomas, Ann. Mag. Nat. Hist., ser. 7, vol. 18, p. 



445, 1906 (classification). 

 Rhipidomys paricola Thomas, Ann. Mag. Nat. Hist., ser. 7, vol. 14, p. 194, 1904 



(type locality, Igarape Agu, on the railway line between Bel6m de Pard and 



Bragan^a, Paril, Brazil; altitude, 50 meters). 

 [Oryzomys (CEcomys)] paricola, Thomas, Ann. Mag. Nat. Hist., ser. 7, vol. 18, 



p. 445, 1906 (classification). 

 CEcomys nitedulus Thomas, Ann. Mag. Nat. Hist., sei. 8, vol. 6, p. 505, 1910 



(type locality, lower Essequibo River, 13 miles above mouth, Demerara, 



British Guiana). — Anthony, Zoologica, vol. 3, No. 13, p. 275, 1921 (Kartabo, 



British Guiana). 

 CEcomys milleri J. A. Allen, Bull. Amer. Mus. Nat. Hist., vol. 35, p. 523, 1916 



(type locality, Barao de Malgago, Rio Conguiaru, upper Gy-Paran^, Rio 



Madeira, Mato Grosso, Brazil). 

 CEcomys florenciae J. A. Allen, Bull. Amer. Mus. Nat. Hist., vol. 35, p. 524, 1916 



(type locality, Florencia, Rio Orteguaza, upper Rio Caquetd, Caquetd, 



Colombia). 

 [?]CEcomys rutilus Anthony, Amer. Mus. Nov., No. 19, p. 4, 1921 (type locality, 



Kartabo, at junction of Cuyuni and Mazaruni Rivers, lower Essequibo, 



Demerara, British Guiana). — Anthony, Zoologica, vol. 3, No. 13, p. 275, 



1921. 

 Rhypidomys [sic] benevolens, Ihering (not Thomas), Rev. Mus. Paulista, Sao 



Paulo, vol. 6, p. 420, 1904 (Rio Jurud, Amazonas, Brazil; skull, 28 mm., 



molar row, 4.3). 



Type: Young adult female, skin and skull (BM 7.1.1.96); collected 

 by Mr. Fraser. 



Type locality: Gualaquiza, Rio Gualaquiza, Santiago-Zamora 

 Province, southeastern Ecuador; altitude, 885 meters above sea level. 



Distribution: From the Amazonian region of Brazil north into 

 the Guianas, west into the foothills of the Cordillera Oriental in 

 Venezuela, Colombia, Ecuador, and the Rlos Ucayali and Huallaga 

 basins of Peru, south into the upper Rio Paraguay drainage basin in 

 Mato Grosso, Brazil; altitudinal range from sea level to possibly 

 1,000 meters above. 



Characters: Those of the species. 



Measurements: See table 5. 



Variation: Six specimens at hand from Zamora are near topotypes. 

 Three are juvenals in old pelage with the new adult pelage appearing 

 along the sides of the body. The three adults are uniformly colored 



