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PROCEEDINGS OF THE NATIONAL MUSEUM 



normal resting position of members of the subgenus Nannobrycon is so 

 different from that of the single known member of the subgenus 

 Poecilobrycon, and indeed from all other known nannostominans, that 

 there is undoubtedly a difference in shape correlated with this sum- 

 ming position. Critical morphological examination of the organs of 

 equilibrium, the swim bladder, and musculature of the caudal fin of 

 all nannostominans will possibly show sufficient differences for 

 Nannobrycon to be retained as a full genus. Braemer and Braemer 

 (1958) have started a project studying the behavior and position of 

 the utricular statolith with reference to Poecilobrycon eques and other 

 characids. 



Figure 10. — Anal fin of Poecilobrycon harrisoni, SL 38.5 mm., SU 50243. 



Poecilobrycon unifasciatus (Steindachner) 



Figure 11 



Nannostomus unifasciatus Steindachner, 1876, p. 127, pi. 9 (original description; 

 localities: Mouth of the Rio Negro and Teflfe on the Solimoens; types in 

 Vienna Museum). — Eigenmann and Eigenmann, 1891, p. 49 (listed); 1910, 

 p. 427 (listed). — Sterba and Tucker, 1962, p. 214 (description and aquarium 

 notes; photographs are of P. harrisoni; also part of color description seems 

 to refer to this species) . 



Poecilobrycon ocellatus Eigenmann, 1909, p. 45 (original description; type locality: 

 British Guiana, Wismar, Demerara River, holotype in Chicago Natural 

 HistoryMuseum);1910,p.427 (listed) ; 1912, p. 286, pi. 37, fig. 4 (description). 



Poecilobrycon unifasciatus — Innes, 1935, p. 158 (description from life and photo- 

 graph). — Axelrod and Schultz, 1955, p. 249 (description and aquarium notes). 



Poecilobrycon eg lies (in part). — Hoedeman, 1950, p. 23. 



Nannostomus ocellatus — Sterbaand Tucker, 1962, p. 214 (description and aquarium 

 notes) . 



Diagnosis. — This species may be distinguished from all other 

 nannostominans examined by the complete absence of a second row 



