152 FISHES OF WESTERN SOUTH AMERICA 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 335; 
Pellegrin, 1904, Bull. Soe. Zool. France, X XIX, 91; 
Pellegrin, 1907, Poiss. Lacs Hauts Plat. Amér. Sud, 17; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 400; 
Evermann and Radeliffe, 1917, Bull. U. S. Nat. Mus., no. 95, 35: 
Eigenmann, 1918c, Mem. Carnegie Mus., VII, 299, pl. xlv, fig. 5. 
Trichomycterus dispar Giinther, 1864, Cat. Fish. Brit. Mus., V, 273; 
Cope, 1877, Proc. Amer. Phil. Soc., XVII, 46; 
Cope, 1878, Proce. Amer. Phil. Soc., XVII, 681, Urubamba, 10,000 feet elevation; Tinta, 
11,400 feet. 
Fic. 19. The Rio Pacaya of the Ucayali basin. Twin-motored canoe of large size 
which was used on this stream. Its waters are brown, and infested with caymans. 
Higher elevations both sides of the Andes and L. Titicacz 
Cope’s specimens may be P. rivulatum. Cope regards Giinther’s specimens 
as maculatum by reason of its smaller number of dorsal radii. With this we can 
agree except that Cope also appears to confuse dispar with rivulatum. Giinther’s 
characterization fits the latter species as well as dispar. He says also that it occurs 
in all parts of Lake Titicaca and its tributaries; eats small molluses, crustacea, and 
fishes; a 14-inch specimen contained one of six inches; brown, reticulated with 
many white lines, sometimes spotted like a trout; adult specimens of less than 
seven inches up to 16; the name maure given to the large ones, suche to the younger 
ones. Cope says the young have a more or less interrupted, lead-colored lateral 
band which breaks up with growth. 
113. Pyaipium RIvuLATUM (Cuvier and Valenciennes) 
Trichomycterus rivulatus Cuvier and Valenciennes, 1846, Hist. Nat. Poiss., X VIII, 495, Guasacona; 
Cope, 1877, Proce. Amer. Phil. Soc., XVII, 46, Lago Titicaca, one large specimen, too few 
dorsal rays to be dispar; 
