56 MEMOIRS OF THE CARNEGIE MUSEUM. 



Genus XIV. Microschemobrycon^^ gen. nov. 



Type : MicroscJieniobrycon guaporensis Eigenmann. 



General appearance of Aphyocharax, the lateral line complete to within four 

 scales of the caudal; three postorbitals, of which the middle one is largest, covering 

 most of the postorbital area; cheeks covered by the third suborbital; maxillary 

 slender, the teeth much crowded, and on less than one-third of its length; teeth 

 narrow, minute, crowded; no pseudo tympanum ; frontal fontanel moderate; adi- 

 pose fin moderate; anal base long. 



29. Microschemobrycon guaporensis, sp. nov. (Plate VIII, fig. 2.) 



6910a, C. M., type, about 37 mm. (30.5 to base of caudal) . Maciel, Rio Guapore, 

 July 23, 1909. Haseman. 



Head 4; depth 4; D. 11; A. 22; scales 4-33-3, twenty-nine or thirty scales 

 with pores; eye 2.75 in the head, snout 3.4, interorbital 3. 



About twelve preventral scales, about nine predorsal scales, occipital process 

 reaching about one-sixth to the dorsal; frontal fontanel not quite 2 in the parietal, 

 its anterior end a little in front of the middle of the eye; mouth large, maxillary- 

 premaxillary border 2.75 in the head; maxillarj^ not nearly reaching third sub- 

 orbital; teeth all minute, those on the mandible conical, with a minute lateral 

 notch, those on the premaxillary broader; twelve teeth on the premaxillary, twelve 

 on the maxillary on less than one-third its length; twenty-five or more on the 

 mandible. Postorbitals in three pieces, the upper and lower ones minute, the 

 middle one high, less strongly developed than in Aphyocharax. 



Gill-rakers 6 -f- 11, long, 2.5 in the eye. 



Origin of dorsal a little nearer snout than base of caudal ; origin of anal under 

 end of dorsal; ventrals almost reaching anal, pectorals not quite to anal. 



Scales well imbricate, firm, without radial striae; caudal and anal naked. 



A series of dots from between the ventrals to the base of the anal and along 

 the root of the anal; some chromatophores on the bases of the caudal rays. 



Genus XV. Oligobrycon^^ gen. nov. 



Type : Oligobrycon microstomus Eigenmann. 



Teeth heavy, tricuspid, in a single series, very few in number (four on the 

 premaxillary); the maxillary not reaching anterior margin of orbit; the eight teeth 

 of the two premaxillaries in a very shallow crescent, maxillary with one to two teeth; 



^^ fuKpoaxvt^s = small of stature. 



'^^ oXiyos = small; Brycon, a genus of fishes. 



