1914.] NATURAL SCIENCES OF PHILADELPHIA. 249 



leaves but very narrow naked strip below, scarcely striate, and its 

 width f of eye. Hind preopercle edge vertically inclined or sloping 

 slightly forward. Opercle narro^', deep, smooth, upper hind edge 

 scarcely emarginate. 



Gill-opening extends, forward opposite front pupil edge. Gill- 

 rakers about 10 + 15, lanceolate, slender, sharp-pointed, about 

 I in gill-filaments, and latter 2 in eye. Isthmus narrowly constricted, 

 surface convex. Branchiostegals rather small, broad, subequal. 



Scales well exposed, large, and disposed in series parallel with 

 1. 1. Caudal base and good portion of lobes, also anal base, covered 

 with smaller scales. Each exposure of scale shows about 8 to 10 

 radiating striae. Ventral with short free pointed axillary scaly flap 

 about I in length of fin. L. 1. complete, slightly decurved or bending 

 doA\ai till about midway in greatest depth, and formed of simple 

 tubes, each extending over about first |^ of scale exposure. From 

 occiput to origin of doi^sal a narrow median naked strip, over which 

 none of scales pass. 



Dorsal origin a little nearer snout tip than caudal base, last simple 

 ray longest and its tip prolonged into a filament extending back far 

 as adipose fin. Latter inserted much nearer caudal base than last 

 dorsal ray base, and fin length trifle less than eye. Caudal well 

 forked, pointed lobes about equal. Anal inserted nearly opposite last 

 branched dorsal ray base, first branched ray longest, though anterior 

 rays not forming lobe. Pectoral broad, pointed, reaches back about 

 opposite first third in depressed ventral. Ventral inserted about 

 opposite dorsal origin and depressed fin extends | to anal origin. 

 Vent at last f in space between ventral and anal origins. 



Color in alcohol largely pale brownish, whitish on sides and below. 

 Head dull brownish above, sides and below whitish. Iris slaty. A 

 dull brownish vertical ill-defined humeral blotch, about third scale 

 from head on vertebral axis and posterior 3 scales, also another less 

 distinct one. Both these blotches with white intermediate area in 

 front. From second dark blotch a narrow dusky vertebral line 

 extends back towards caudal base, though ends abruptly before 

 latter. Throughout its course it gradually expands and finally 

 results in a spot on the side of caudal peduncle. Fins all pale and 

 all more or less tinged with grayish. Front edges of dorsal, anal, 

 and especially ventral, dusky. Adipose fin dusky. Median dark 

 streak dowTi back. 



Length 80 mm. . 



Type, No. 39,332, A. N. S. P. Rupununi River, British Guiana. 

 J. Ogilvie. 



