6Q Synopsis of the Fresh Water Fishes, 



JVasal apertures near the antero-superior corners of the eyes. 



Operculum with a posterior triangular dilatation, from the 

 extremity of which* issues a more or less long and slender com- 

 pressed process. 



Lateral line deflected at its commencement, but soon con- 

 tinued in a straight line, on the flank, to the caudal fin. 



Dorsal posterior, above the middle of the anal, much higher 

 than long, v/ith the base short. 



Anal long, of moderate height, and decreasing posteriorly. 



Caudal deeply forked, with the lobes of nearly equal length. 

 Yentrals very small, pointed. 



Pectorals moderate, pointed, with the superior rays longest. 



The most important peculiarity, which distinguishes this genus 

 from Stevardia, is tlie claviform extension of the operculum. 



Corynopouia Riisei, Gill. 



The general shape of the body is similar to that of the 

 Steiiardia alhipinnis. The head, from the snout to the end of 

 the crest of the external occipital, forms about one seventh of the 

 entire length, inclusive of the caudal fin, and exclusive of it, a 

 fifth. The distance from the snout to the margin of the pre- 

 operculum is nearly as great as to the crest. The claviform 

 prolongation of the operculum is most slender at the posterior 

 third of its length, and is slightly deflected in the direction of 

 the anus ; it advances but little beyond the inner angle of the 

 base of the pectoral. The eyes are about two fifths of the 

 length of the head from the snout to the occipital crest, and are 

 separated from each other by a space nearly equal to one of 

 their diameters ; much less than that distance intervenes be- 

 tween them and the snout. The height of the body is greatest 

 at the middle, and is there about a third more than the length 

 of the head. 



