eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 387 



242. Catoprion mento (Cuvier). (Plate LVI, fig. 3.) 

 Serrasalmo mento Cuvier, Mem. Mus. d'Hist. Nat., V, 1819, 369, pi. 28, fig. 3. 

 Catoprion mento Muller and Troschel, Horse Ichth., I, 1845, 22, pi. 2, fig. 5.— 

 Cuvier and Valenciennes, Hist. Nat. Poiss., XXII, 1848, 304. — Muller 

 and Troschel, in Schomburgk, Reisen, III, 1848, 637 (Lake Amucu). — Kner, 

 "Familie der Characinen," ii, 1859, 26 (Rio Guapore; Rio Negro). — Gunther, 

 Catalogue, V, 1864, 379. — Eigenmann and Eigenmann, Proc. U. S. Nat. 

 Mus., XIV, 1891, 61. — Eigenmann, Repts. Princeton Univ. Exp. Patagonia, 

 III, 1910, 442. 

 Mylesinus macropterus Ulrey, Ann. N. Y. Acad. Sci., VIII, 1895, 296 (Brazil). 

 One specimen, 148 mm. Rockstone. (C. M. Cat. No. 1739.) 

 Three specimens, 75-79 mm. Konawaruk. (C. M. Cat. No. 1740a-6; I. U. 

 Cat. No. 11640.) 



Head 3.66-4; depth 1.4-1.75; D. 16 or 17; A. 37-39; lateral line 89-94; ven- 

 tral serrse 33; eye 2.66 in the head, 1 in the interorbital, .75 in the snout. 



Rhomboidal; snout very short, sharply pointed, lower jaw much projecting, 

 entering profile; premaxillary with two large, antrorse, conical teeth in an outer 

 series, and three much smaller teeth forming an inner series. 



Gill-rakers long and slender, 9 + 14. Lateral line with a sag to below the 

 end of the dorsal ; anal entirely naked. Dorsal and anal falcate, the dorsal reaching 

 beyond the middle of the upper caudal lobe, and the anal lobe to the last ray of the 

 dorsal in extreme cases; adipose more than half the length of the dorsal; caudal 

 forked. Silvery, anal lobe pink at base; caudal with a basal, V-shaped black spot. 



Mylesinus Cuvier and Valenciennes. 

 Mylesinus Cuvier and Valenciennes, Hist. Nat. Poiss., 1848, 234. 



Type, Mylesinus schomburgkii Cuvier and Valenciennes. 



Abdomen rounded in front of the ventrals, serrate behind them; premaxillary 

 with six or seven teeth in each side in the front series, of which the first and (if 

 seven) the last are smallest; in the second series two teeth of similar form behind 

 the space between the second and third teeth of the first series and close to them; 

 mandible with seven to thirteen teeth on each side; base of anal scaled. Teeth 

 all flat, thin incisors. Premaxillary teeth three-lobed, the middle lobe much the 

 broader; teeth of the lower jaw flat, rounded, with a notch in front which receives 

 a lobe of the preceding tooth. Dorsal rays prolonged, filiform; jaws nearly equal; 

 anal bilobed; rays in both sexes (during breeding season ?) bifid, one fork turned 

 to the right, the other to the left. 



