eigenmann: the freshwater fishes of British guiana 311 



Occipital process short, the fontanel large, oval, separated from the small 

 frontal fontanel by a convex bridge on a level with the rest of the skull; suborbitals 

 narrow, leaving most of the cheek naked. Mouth small, maxillary-premaxillary 

 border 2.8 in the head; maxillary not quite equal to the eye. Teeth all long, 

 tricuspid, in a single series, about eleven in the premaxillary, about five in the 

 maxillary. 



Gill-rakers 7 + 9, about equal to the pupil. 



Origin of dorsal nearer to snout than to caudal, its rays of nearly uniform 

 height, none prolonged. Anal considerably shorter than the dorsal, its middle 

 rays highest, reaching in the male to middle of caudal; origin of anal under one 

 of the last four dorsal rays; origin of ventrals and dorsal equidistant from snout; 

 tips of ventrals reaching to the anal in the male, the ventrals slightly shorter in the 

 female. Pectorals not quite reaching ventrals. 



Scales cycloid, regularly imbricate, no interpolated scales. No scales on the 

 anal, those along the base forming a sheath. Caudal naked. A very minute 

 axillary scale. 



Back dusky, margined by a darker stripe from above eye to upper caudal lobe. 

 A light band from upper part of eye, becoming widest under the middle to end of 

 dorsal in the male, widest on caudal peduncle, contracted on caudal fin in the 

 female. A dark band from eye to upper part of gill-opening, thence descending to 

 meet its fellow on the lower surface and edge of caudal peduncle, thence curved 

 up on the caudal to tips of its middle rays; this band more intense, jagged, and 

 more strongly decurved in the male than in the female. Sides of caudal peduncle 

 with a rusty spot on each scale (female) ; dorsal in both sexes nearly uniform, 

 darkest in the male. Upper margin of caudal geranium-red, most intense in the 

 male, below which is a continuation of the upper dark band of the sides, fading out 

 toward tip of upper lobe and with oval hyaline spots; a wedge-shaped area at 

 middle of caudal and all but the base of some of the rays of the lower lobe hyaline. 

 Tij) 0I ana l i n male scarlet, below which is a broad dark band, base and last rays 

 hyaline. Last rays of anal (female) hyaline, otherwise dark with conspicuous 

 round or oval hyaline spots. Ventrals slightly dusky. Pectorals hyaline. 



Subfamily APHYOCHARACiNiE. 

 Odontostilbe Cope. 

 Odontostilbe Cope, Proc. Am. Philos. Soc, XI, 1870, 566. 

 Type, Odontostilbe fugitiva Cope. 



Minute fishes, with multicuspid incisors in a single series in each jaw, and a 

 complete lateral line. 



