ANNOTATED LIST OF THE SPECIES 155 
Markings obscure in older specimens, becoming more olivaceous with age, 
while in rivulatum the spots become more pronounced in the larger. 
Higher up the Mantaro, in the slower, more sluggish streams and lakes of 
the pampas (13000 feet and above), such localities as Zigzag, Tilarnioc, and Junin, 
we find the specimens more elongate, the lappets not usually bulbous, and the 
color brown with no indication of an olivaceous tint. 
Our first specimens were collected in the diminutive type stream, the Rio 
Oroya, where it rushes precipitously among rocks, boulders, and rubble for a half- 
mile to join the Rio Mantaro. The roots of the cubé plant were used here for the 
first time; the bruised pulp and milky extract were placed in the stream at the 
top of the canon, into water so turbulent that you would not expect to find any 
life. But ina short time the Pygidiwm began to boil out from among the rocks in 
enormous numbers, struggling for breath, and were easy victims to the dipnet. 
This was a surprise even to the bystanders. 
115. PyarpiuM TACZANOWSKIL (Steindachner) 
Pygidium dispar Tschudi, part, 1845, Fauna Peru., 22, pl. iii, lower figure. 
Trichomycterus taczanowskii Steindachner, 1882, Denksch. KIX. Akad. Wiss. Wien, XLVI, 22, pl. iv, 
figs. 1-1b, Rio de Huambo, Rio de Tortora. 
Pygidium taczanowski Eigenmann and Eigenmann, 1889, Proc. Cal. Acad. Sei., (2), II, 52; 
Eigenmann and Eigenmann, 1890, Oce. Papers Cal. Acad. Sci., I, 338; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 400; 
Higenmann, 1918, Mem. Carnegie Mus., VII, 301, pl. xlvi, figs. 5-8; 
Pearson, 1937a, Proce. Cal. Acad. Sci., (4), XXIII, 93, Maranon. 
Central Peru northward in moderate elevations 
17817, 17, 130-226 mm., Rio Huallaga, Hudnuco, Allen, October, 1918. 
17818, 8, 45-69 mm., Rio Tingo, Hudnuco, Allen, October, 1918. 
The latter specimens all much smaller in this small tributary stream than in 
the nearby Huallaga into which it flows. 
Steindachner was given the local name kutschin for this species. My inform- 
ants usually applied the name bagre, meaning catfish, though others were calling it 
huascachallhua. 
In many respects our Hudnuco specimens show a close correspondence to the 
original descriptions: D.9; A. 7; P. 9; width of head in its length 1.3; snout 2.1—-2.3; 
interorbital 3.3-near 4, as compared with the broader 3.0-3.33 of the original 
description; nasal barbels 1.3; lower barbels 1.6; width of mouth in head 2; eye in 
front of middle to middle of head. Our specimens unlike the types in that the 
origin of the dorsal is nearer the caudal than to the gill-opening in those of about 
130 mm., and in our largest 1.4 nearer the caudal as compared with 1.22 nearer in 
the types. The ratio of the first pectoral ray to the length of the head about the 
same. ‘These measurements indicate greater variability in the young rather than 
a progressive advancement caudally of the dorsal fin with age. 
