154 FISHES OF WESTERN SOUTH AMERICA 
with a funnel beneath, and suspended from a balsa by means of a native grass 
rope. In general the largest and best-conditioned specimens came from lakes. 
Pearson (1924) collected P. rivulatum as far down into Bolivia as the fringe 
of the foothills at about 1500 feet elevation. His specimens show variations which 
are about constant within each locality. He finds none of the typical vermicula- 
tions of the upland specimens, but the spots are large or small, in horizontal lines, 
or irregular. His fluviatile specimens have larger barbels than those of lakes. 
His collections and those reported above show that diligent search has been made 
over a wide territory without bringing to light any specimens which we could 
identify as P. dispar, which may therefore fall within the wide range of variation 
of rivulatum, in case a few errors have been made in describing it. 
While not a rival in numbers or amount marketed in the Titicaca valley, it 
outranks its competitor Orestias in size and quality. The flesh is soft and there 
are few bones. Suggesting Ameturus of North America in form, the bottom- 
inhabiting habit is likewise similar. 
114. Pyaiprum oroyAE Eigenmann and Eigenmann 
Pygidium oroyae Eigenmann and EFigenmann, 1889, Proc. Cal. Acad. Sci., (2), I, 51; 
Eigenmann and Eigenmann, 1890, Occ. Papers Cal. Acad. Sci., I, 334, 8 specimens, R. Oroya, 
Pochachara; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 399; 
Evermann and Radeliffe, 1917, Bull. U.S. Nat. Mus., no. 95, 35, pl. iv, fig. 2, Oroya; 
Eigenmann, 1918, Mem. Carnegie Mus., VII, 304, text fig. 10. 
Rio Mantaro, central Peru, having a very restricted range, not extending far 
from the valley of the small river which gives it the name, except that it has in- 
vaded the upper Perené. 
17799, many hundreds, 20-206 mm., Rio Oroya and Rio Mantaro, Oroya, Eigenmann and Allen, 
September, 1918. 
17800, many hundreds, 20-102 mm., Tarma, R. de Tarma, Eigenmann, September, 1918. 
— , Many, , Tarma, R. de Tarma, and springs, Allen, June, 1920. 
—, 18, 24-90 mm., Tarma, Lola E. Vance, about 1912. 
17801, 11, 35-135 mm., Zigzag, branch R. Mantaro, Allen, October, 1918. 
17802, 2, 137-184 mm., creek, L. Chinchaycocha, Allen, October, 1918. 
17803, many, 36-110 mm., Tilarnioc, R. Mantaro, Eigenmann, September, 1918. 
17804, 2, 94 and 115 mm., Pachachaca, Eigenmann, September, 1918. 
17805, many, 22-82 mm., Huancayo, Eigenmann, September, 1918. 
17806, 26, 20-71 mm., Quebrada, Huanecayo, Kigenmann, September, 1918. 
17807, 1, 115 mm., Jauja, Eigenmann, September, 1918. 
17808, 3, 830-77 mm., Palea, Peru, Eigenmann, September, 1918. 
Originally described from eight specimens, the description amplified by 
Evermann and Radcliffe, 1917, from the examination of two. We have before 
us many hundreds reaching a maximum of 206 mm. compared with former maxima 
of 140 mm. and 130 mm., and collected from a wide range of localities. 
The dorsal fin overlaps the anal; ventrals much reduced; the caudal rounded 
in the younger, becoming subtruncate in the larger; pectoral short and rounded, 
first ray not prolonged; anal fin large; fins becoming thick and fleshy with age; 
lappet at angle of mouth triangular and bulbous. 
