eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 491 



Cotypes, sixteen specimens, 80-170 mm. Amatuk. (C. M. Cat. No. 2394a-d; 

 I. U. Cat. No. 12530.) 



Cotypes, twenty-five specimens, 34-115 mm. Tukeit. (C. M. Cat. No. 

 2395a-e; I. U. Cat. No. 12531.) 



Cotypes, twenty-seven specimens, 20-130 mm. Savannah Landing. (C. M. 

 Cat, No. 2396a-e; I. U. Cat. No. 12532.) 



Cotypes, three specimens, 51-118 mm. Creek between Kangaruma and 

 Potaro Landing. (C. M. Cat. No. 2397a-6; I. U. Cat, No. 12535.) 



Cotype, one specimen, 85 mm. Crab Falls. (C. M. Cat. No. 2398a.) 



Cotype, one specimen, 44 mm. Two hours below Holmia. (C. M. Cat. No. 

 2399a.) 



Cotypes, five specimens, 25-65 mm. Aruataima. (C. M. Cat. No. 2400a-c; 

 I. U. Cat. No. 12533.) 



Cotypes, three specimens, 45-67 mm. Erukin. (C. M. Cat. No. 2408a-o; 

 I. U. Cat. No. 12534.) 



Cotype, one specimen, 60 mm. Konawaruk. (C. M. Cat. No. 2401a.) 



Cotype, one specimen, 28 mm. Waratuk. (C. M. Cat. No. 2402a.) 



Evidently very closely related to M. tetramerus, from which it can easily be 

 distinguished by the dark band from the eye through the angle of the preopercle. 



Head 3; depth 2.28; D. XIV,10; A. 111,8; lateral line 16 + 8 to 11 + -fc; 

 scales 24 to 26 along a median series; eye 3.66 in the head, 1 in the preorbital, 1.66 

 in the interorbital, in the largest; eye a little behind the middle in the largest. 



Lateral line rarely forked on the caudal; last dorsal spine less than half the 

 length of the head. 



Sides with six cross-bands; a dark band from the eye to the spot at the base of 

 the upper caudal rays, intensified where it crosses the Vertical bands, the spot below 

 the middle of .the lateral line largest; a spot at the base of the upper caudal lobe; 

 a dark band from the eye to a little in front of the angle of the preopercle; last 

 parts of dorsal and upper half of caudal with hyaline spots. 



334. uEquidens tetramerus (Heckel). 



Acara tetramerus Heckel, Ann. Wiener Mus., II, 1840, 341 (Rio Branco). — Muller 

 and Troschel, in Schomburgk, Reisen, III, 1848, 624 (Lakes Tapacuma, 

 Capoye, and Amucu). — Gunther, Catalogue, IV, 1862, 277 (Guiana; Rio 

 Branco). — Cope, Proc. Acad. Nat. Sci. Phila., 1872, 255 (Ambyiacu). — Stein- 

 dachner, "Chromidcn Amazonenstromes," 1875, 5 (Tabatinga; Teffe; Obi- 

 dos; Villa Bella; Cudajas; Santarem; Gurupa; Para; Rio Hyutay; Tajapuru; 



