NO. 3538 CHARACID FISHES — WEITZIVIAN 3 



at hand. The primary function served by this paper is to point out 

 our present state of knowledge concerning these fishes and to indicate 

 problems for future study. 



Counts and measurements were taken from the left side of each 

 specimen. In the descriptions the initial values are the arithmetical 

 means, and the values included in parentheses are the extremes of all 

 specimens cited in the material examined. Measurements were taken 

 from adult specimens only. 



The following straight-line measurements were made from the 

 anteriormost part of the fleshy tip of the upper jaw to some point 

 posterior on the body surface. Standard length (SL) was measured 

 to the posterior end of the hypural fan. Predorsal length was meas- 

 ured to the anterior base of the first dorsal fin ray. Preanal length 

 was taken to the anterior base of the most anterior, visible anal fin 

 ray. Head length was measured to the most posterior border of the 

 opercular bone, not the fleshy flap which was often damaged. 



Eye length is the greatest distance between the posterior border of 

 the first infraorbital and the anterior border of the fifth infraorbital 

 bone. Depth was measured from the anterior dorsal fin base ver- 

 tically to the median profile of the belly. Least depth of caudal 

 peduncle was measured vertically. Length of caudal peduncle was 

 measured from the posterior base of the last anal fin ray to the posterior 

 end of the hypural fan. Interorbital width is the least width between 

 the lateral supraorbital borders of the frontal bones. 



Vertebral counts were taken from radiographs and include the 

 vertebrae forming the pars sustentaculum of the Weberian apparatus 

 and the ultimate vertebra with its urostyle. 



Fin counts: The ultimate (posterior) ray of the dorsal and anal 

 fins was counted as one when one ray was associated with the last 

 pterygiophore and as two when there were two entirely separate rays 

 associated with the last pterygiophore. Counts were least variable 

 when this method M^as employed. All anterior rudiments of fin rays 

 were counted. Unbranched rays (except the most posterior ray of 

 the dorsal, anal, pectoral, or pelvic fins) are designated by low^ercase 

 roman and branched rays by Arabic numerals. The principal caudal 

 fin ray count includes all rays associated with the hypural elements 

 and may be taken without recourse to examining the hypural fan by 

 counting all branched rays and adding two. The count of the upper 

 lobe is given first, followed by a bar (/) and then the count of the rays 

 of the lower caudal lobe. 



Gill-raker counts in these small fishes can be made most accurately 

 on ahzarin-stained specimens and all such counts were confined to 

 such specimens. The counts are of the bony supports of gill rakers. 

 Scale counts in a lateral series refer to all scales in a median lateral 



