eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 393 



Nat. Mus., XIV, 1891, 60.— Ulrey, Ann. N. Y. Acad. Sci., VII, 1895, 299 



(Brazil). 

 Mijlcus rhomboidalis Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 443. 

 Tetragonopterus latus Schomburgk, Fishes Brit. Guiana, I, 1841, 241. 

 Myletes latus Muller and Troschel, Horse Ichth., I, 1845, 37; in Schomburgk, 



Rcisen, III, 1848, 638 (all rivers). 



One specimen, 20 mm. Konawaruk. (C. M. Cat. No. 2462a.) 



Two specimens, 130-219 mm. Tumatumari. (C. M. Cat. No. 1490a; I. U. 

 Cat. No. 11659.) 



One specimen, 19 mm. Gluck Island. (C. M. Cat. No. 2463a.) 



Seven specimens, the largest 47 mm. Warraputa. (C. M. Cat. No. 1103a-c; 

 I. U. Cat. No. 11664.) 



Eight specimens, the largest 40 mm. Amatuk. (C. M. Cat. No. 1105a-6; 

 I. U. Cat. No. 11663.) 



One specimen, 59 mm. Crab Falls. (C. M. Cat. No. 2221a.) 



One specimen, about 104 mm. Bartica. (C. M. Cat. No. 2461.) 



I have also examined the specimens in the British Museum, the largest of 

 which is 260 mm., and those in the Berlin Museum under the head of lahis. 



Most of the specimens secured were young from the cataracts at Warraputa, 

 Amatuk, and Crab Falls. 



Head 3.66; depth 1.5; D. 23-24; A. 35 and 36; seme 37-41; eye 2.75 in the 

 head, 1.5 in the interorbital. Most readily distinguished by the short-rayed dorsal 

 and long adipose dorsal. 



Myleus Muller and Troschel. 

 Myleus Muller and Troschel, Horse Ichth., I, 1845, 24 (setiger = pacu). 

 Tometes Cuvier and Valenciennes, Hist. Nat. Poiss., XXII, 1848, 226 (trilobatus 



= pacu). 



Type, Myleus setiger Muller and Troschel = Myletes pacu Schomburgk. 



Belly trenchant, serrate, the serrse becoming obscure with age; the two pre- 

 maxillary series of teeth close together, the outer incisor-like; mandible with a 

 pair of conical teeth in front; anal falcate in the female, bilobed in the male; 

 dorsal rays prolonged into filaments in the male. 



250. Myleus pacu (Schomburgk). (Plate LIX, figs. 1-6.) 



Myletes pacu Schomburgk, Fishes Brit. Guiana, I, 1841, 236, pis. 20-21. — Muller 

 and Troschel, in Schomburgk, Reisen, III, 1848, 644. 



