100 bulletin: museum of comparative zoology. 



A highly iridescent-blue stripe along one row of scales between base of pectoral 

 and middle of anal fin. 



Distal f-f of dorsal much darkened, especially in males ; distal half of the first 

 five, and tips of most of the remaining anal rays, the middle caudal rays, and the 

 ventrals, also blackish. A silvery lateral band, f of a scale wide from eye to 

 caudal, below which is a grayish-brown stripe, faint and terminating in the middle 

 of the caudal fin. A vertically elongate, roughly diamond-shaped, humeral spot, 

 margined on each side by a faint, silvery line. Pale, bluish-gray iridescence below 

 the stripes. 



One hundred and three specimens, 42-52 mm. long (the type of 46 mm.) 

 Manacapuru. Win. James. 



Hemigrammus levis Dcrbin, sp. nov. 



Head 3.5-3.66 ; depth 3.2-3.6 ; D. 11, rarely 10 ; A. 17-20; scales 5-30 to 

 34-3£, 5 to 11 with pores; eye 2.5-2.66 in head; interorbital slightly less than 

 eye. 



Maxillary without teeth ; a round caudal spot, other fins plain ; a slaty-black 

 lateral band below the dorsals and a silvery band below it. 



Over 300 specimens, 33-47 mm. long. Lago do Maximo, Obidos, Villa Bella, 

 Lake Jose Assu. 



Hyphessobrycon Durbin, subgen. nov. 



This genus is a Hemigrammus with a naked caudal. 

 Type. — Hyphessobrycon compressus (Meek). 



Hyphessobrycon compressus milleri Dcrbin, subsp. nov. 



Sides of head and body everywhere with numerous chromatophores ; dorsal 

 dark. Maxillary considerably less than the length of the eye. Second suborbital 

 covering two-thirds of cheek, otherwise as in H. compressus. 



One specimen, 40 mm. long. Los A mates, Guatemala. 



Hyphessobrycon serpae Durbin, sp. nov. 



Head 3.5 ; depth 2f-3 ; A. 27-30. D. 10, rarely 11 ; scales 5-5+24-3£; eye 

 25-2.75 ; interorbital 3+. 



A round, black spot of variable size on the dorsal, margined above on the 

 second and third rays with white and below by a narrow white bar, which is widest 

 on the first ray. Bases and tips of all the rays but the first without pigment ; a sub- 

 marginal bar of black on the first anal rays, and distinct marginal bar on the last 

 rays. Some specimens with the intermediate rays also tipped with black. A 

 humeral spot. 



20985. Forty-six specimens, 26-30 mm. long. Serpa. 



