ANNOTATED LIST OF THE SPECIES 209 
Cuvier and Valenciennes, 1840, Hist. Nat. Poiss., XV, 459: 
Giinther, 1864, Cat. Fish. Brit. Mus., V, 255; 
Cope, 1878, Proc. Amer. Phil. Soc., XVII, 681, Rio Maranon; 
Eigenmann and Eigenmann, 1889, Proce. Cal. Acad. Sci., (2), II, 36; 
Eigenmann and Eigenmann, 1890, Oec. Papers Cal. Acad. Sci., I, 382; 
Regan, 1904, Trans. Zool. Soc. London, XVII, 292; 
EKigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, ITI, 415; 
EFigenmann, 1912, Mem. Carnegie Mus., V, 243. 
The Amazons and Guianas 
15390, 1, 186 mm. to end of middle caudal rays, Rio Huallaga, Yurimaguas, Allen, November, 1920. 
Head 5 to end of plate on side of caudal; depth 11; D. I, 7; A. 6; scutes 21 + 14; 
the keels approximated, not united from the 22d on; width of head 1.33 in its length, 
its depth 2.6, eye 6.5, interorbital 5.33; about 7 spoon-shaped teeth in the upper 
jaw, about 9 similar but shorter ones in the mandibular ramus; lips with numerous 
papillae over and covering their entire surface, those along the margin of the lower 
lip bifid, those along the lateral edge, on the margin of the barbel, each with from 
one to four lateral papillae; barbel reaching to base of pectoral spine; interorbital 
smooth, slightly convex, without keels; snout near nares tumid; occipital with a 
single low crest, the two plates behind it bicarinate, the predorsal plate with a single 
keel; a feeble keel from opposite the middle of the base of the dorsal forward; head 
naked below, covered with the lips except the marginal granular area which is 
extended inward in front of the gill-opening; ventral surface covered with small 
plates from the anus to the lips, anterior margin of the armored part convex, extend- 
ing forward of the angle of the gill-opening; no preanal plate; about three series of 
granular plates between the lateral scutes in front of the ventrals, about 7 near the 
pectorals; pectoral spines very heavy, reaching ventrals, outer ventral rays to end 
of anal basis; anal rounded, shorter than head; dorsal slightly emarginate, the first 
ray extending the width of a scute beyond the last when the fin is depressed; upper 
caudal ray produced. Pectoral and inner part of ventrals blue black; dorsal with 
a streak of the same color along the posterior half of the membranes, interrupted 
on the first half of the fin; caudal with a blue black bar across the middle of the 
upper lobe and continued along the margin of the middle rays and of lower lobe; 
anal without markings. 
15391, 1, 212 mm., Rio Itaya, Iquitos, Allen, September, 1920. 
Barbels much shorter, not covering the surface of the lips; plates of the ventral 
surface forming a straight line between gill-openings; width of head 1.25 in its 
length; occipital with a pair of closely approximated crests; anal and dorsal trun- 
cate, the first dorsal ray slightly prolonged, outer pectoral ray extending beyond 
base of ventrals, outer ventral ray beyond base of anal; dorsal, pectorals and ven- 
trals dark, with lighter spots, anal with a few dark spots, caudal spotted, 4 dark 
cross-shades behind the dorsal. 
15980, 9, 146-215 mm., Iquitos, Morris, 1922. 
15393, 1, 58 mm., Gosulimacocha, Allen, October, 1920. 
15400, 1, 66 mm., Rio Paranapura, Allen, October, 1920. 
