48 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



graphical origin. Caudal fin with principal rays 10/9; distal tips of 

 8 principal rays in upper lobe and 11 in lower lobe. 



Anal fin of males enlarged and modified, but not as greatly as in 

 Nannostomus digrammus. Second undivided ray expanded anteriorly 

 and posteriorly, giving this ray a flattened appearance. Posterior 

 margin of this ray fits into recess formed by 2 ray halves of expanded 

 and flattened third unbranched ray behind. First, second, and third 

 branched rays shghtly flattened and expanded, first to greatest extent. 

 These rays slightly ribbed. Rest of anal fin rays almost normal, 

 being only shghtly heavier than usual type of characid fin ray. In- 

 chnator muscle attached to ninth ray only. 



Figure 12. — Poecilobrycon eques, male, SL 29.0 mm., SU 50299. 



Radial grooves of scales in third horizontal scale series below 

 dorsal fin quite variable but general pattern shown in figure 12. 

 Posterior field may have 1 to 4 radial grooves, anterior field 2 to 6 

 radial grooves and dorsal and ventral fields one radial groove each. 

 Scales in a lateral series 24 to 25, no lateral-line scales and 11 or 

 12 predorsal scales. Total number of vertebrae 33 to 34, usually 

 18 to 19 precaudal and 15 caudal vertebrae. 



Color in alcohol. — Top of head light brown. Nape, areas 

 immediately above nares and eyes, central parts of frontals, and 

 tip of snout, dark brown. Primary horizontal stripe beginning at 

 tip of snout and lower jaw, extending posteriorly over first infra- 

 orbital to pupil of eye. Then extending from posterior edge of 

 pupil to posterior edge of opercular bone. On opercle width of 

 this stripe somewhat variable. On body, primary horizontal stripe 

 beginning under fleshy opercular flap and extending posteriorly 

 through entire fourth and fifth scale rows. In some specimens upper 

 two-thirds of fourth scale row free of heavy pigment. Over anal fin 



