eigenmann: the cheirodontin^. 



57 



cheeks with a very narrow naked margin; three postorbitals ; lateral hne incom- 

 plete; scales with few divergent radial striae; caudal naked; adipose well-developed. 

 Interhsemals not evident; no pseudotympanum. 



This genus differs from Aphyocharax and from Mixobrycon ribeiroi in dentition, 

 the size of the mouth, the armature of the cheeks, etc. 



30. Oligobrycon microstomus sp. nov. (Plate IX, fig. 1.) 

 6898a, C. M., type, 39 mm.; 6899a, C. M., paratype, 27 mm. Jacarehy, Rio 



Parahyba, July 15, 1908. Haseman. 

 Very similar in shape, size of mouth, and general appearance to Cheirodon 

 interrwptus. 



Head 3.5; depth 2.3-2.6; D. 11; A. 24 or 25; scales 7 or 8 + 25, twelve scales 



Fig. 17. Oligohrycon microstomus 'EAgsnms.rai.. 6699, C. M. a, outline of top of head; 6, c, d, premaxil- 

 lary, maxillary, and mandible enlarged; e, dentition of specimen 6898, C. M. ; /, suborbitals and postorbitals of 

 6699, CM. 



between dorsal and ventrals ; eye three times in the head, a little less than interorbital ; 

 caudal peduncle as deep as long; base of anal a little longer than head. 



Very deep and compressed; dorsal and ventral profiles nearly equally arched; 

 preventral area rounded, without a definite median series of scales; predorsal area 

 with a blunt keel; about eight scales in a median series from the dorsal forward 



