ATELEUS 27 



extending their range into Colombia, the latter going even to Peru. A. 

 RUFiVENTRis is doubtfully from Panama, the type coming from the Rio 

 Atrato in Colombia. In the Guianas, and on the banks of the Orinoco, 

 and also on those of the Lower and Upper Amazon with such tribu- 

 taries as the Rio Madeira, R. Marmore, R. Guapore and R. Carari, and 

 ranging as far to the westward as the Rio Maranon, Peru, A. p.vnis- 

 cus occurs. On the Upper Rio Cauca, a tributary of the Orinoco, A. 

 VARIEGATUS is met with, ranging westward into Peru in the Province 

 of Jean de Bracamorros, and at Chayavetas, Nautuas and Elvira, 

 Peruvian Amazons. A. marginatus is found in the vicinity of Para, 

 Lower Amazon, and on the banks of the Rio Tocantins. Above the 

 great rapids of the Orinoco, at Atures and Maypures, A. belzebuth 

 occurs ; and in Colombia in the Valley of the Magdalena, A. hybridus 

 is supposed to dwell. A. fusciceps has only been met with in the 

 trans-Andean districts of Ecuador. There remain two rather doubtful 

 species whose habitats are quite unknown, A. grisescens and A. 



CUCULLATUS. 



KEY TO THE SPECIES. 



A. Head and back black. 

 0. Under parts black. 



a.' Face flesh color. 



a." Forehead, crown and whiskers black. . .A. paniscus. 



b." Forehead, crown and whiskers white..^. marginatus. 

 b.' Face black A. ater. 



b. Under parts, grayish yellow A. variegatus. 



c. Under parts bright rufous 4. ruHventris. 



B. Head and back mixed black and silvery gray or golden. 



a. Hair on head not projecting over forehead; back 



more black than gray A. grisescens. 



b. Hair on head projecting over forehead ; back more 



gray than black A. cucullatus. 



C. Head black, back blackish chestnut grading into golden. 



a. Under side of arms and legs grayish yellow A. belzebuth. 



b. Under side of arms and legs mostly black, yellow 



restricted to narrow line on forearm A. pan. 



D. Head yellowish wood brown, back black tinged with 



burnt umber brown A. fusciceps. 



E. Head buff, back grayish drab, (typical) A. geoffroyi. 



F. Head blackish brown, triangular white mark on fore- 



head ^- hybridus. 



