518 PROCEEDINGS OF THE ACADEMY OF [Jl^llv, 



Depth 3^-; head 4; D. 10; A. 19; scales 33, seven perforated. Slen- 

 der, elongate; dorsal and ventral profiles equally arched. Head 

 pointed, mouth small, oblique, the lower jaw slightly projecting; 

 eye twice as long as snout, 2^ in head. Seven teeth in each inter- 

 maxillary, 2-3 in each maxillary, 10 in each side of the mandible. 

 Maxillary little beyond vertical from front of orbit. 



Origin of dorsal much behind ventrals, equidistant from tip of snout 

 and middle of caudal lobes. Caudal moderately forked. Pectorals 

 reaching to ventrals, ventrals not to anal. None of the rays filiform. 



Straw colored, upper surface peppered with pigment cells, tip of 

 lower jaw and snout dusky. No distinct markings. 



In the table below is given the measurements of 16 specimens: 



Min. Max. Average. 



Length in mm 34.0 41.0 36.11 



Anal 19.0 23.0 



Depth 3.0 3.75 



Head 3.75 4.2 



Eye 3.0 3.33 



Perforated scales 6 9^ 



[ Intermaxillary 13 16 



Teeth Maxillary 2 3 



[ Mandibular 18 20 



Scales 5 to 5.5-30 to 34-4.5 to 6. 



63. Hemigrammus melasopterus sp. nov. 



Type No. 10,039 (245), 37 mm. From Aguada, near Arroyo Tremen- 

 tina. December, 1900. 



Co-types No. 10,040, one specimen (244), 35 mm. From Aguada, 

 near Arroyo Trementina, December, 19 . 



Co-types No. 10,041, five specimens (216), 29-35 mm. Taken in a 

 trap in the Arroyo P3qDucu. Januar}^, 1901. 



A moderately elongate species. Depth 2§. Profile of snout 

 abruptly rising, slightly concave at the nape, rising gently and convex 

 to the origin of the dorsal. Lower jaw slightly projecting, maxillary 

 toothless, long, extending obliquely downward and backward to the 

 middle third of the eye. The upper edge of the opercle emarginate. 

 The subopercle large. 



Eye large, 2^ in head, | in interorbital, ^ in snout. 



Lateral line 34, incomplete, only the first five scales perforated. 



The fins large. The height of the dorsal greater than the length of 

 the head by ^ the diameter of the eye. Last dorsal ray 2J in the 

 highest ray. 



Caudal deeply divided, its lobes subequal. 



