ANNOTATED LIST OF THE SPECIES 151 
Kigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 399; 
Eigenmann, 1918c, Mem. Carnegie Mus., V, 288. 
Type: Pygidium fuscum Meyen 
Panama to Chile and Patagonia, inhabiting mountain lakes and streams, rarely 
lowland streams to near sea level, the species usually limited to a few 
closely connected drainage areas 
Of elongate body form, cylindrical to terete, caudal peduncle compressed and 
elevated; without scales or plates, two barbels at each angle of mouth, no mental, 
generally short; eye small and at or before middle of head, without free orbital 
border; interopercle with several series of spines; gill-membrane narrowly united 
with isthmus, and usually a narrow, free margin across it; mouth terminal, moder- 
ate; Jaws with two or more chisel-like teeth, sometimes conical; no labial or vomerine 
teeth; fins without spines, although sometimes filamentous; ventral fins at or beyond 
middle of body. 
110. PyGipium ruscum Meyen 
Pygidium fuscum Meyen, 1835, Reise in Peru, I, 475; 
Tschudi, 1845, Fauna Peru., 21; 
EKigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 399; 
Eigenmann, 1918c, Mem. Carnegie Mus., VII, 298. 
Peru, in the High Andes 
Aside from Tschudi’s assurance that P. fuscum is distinct from his own dispar, 
there is no corroboration of the existence of this species with its unsatisfactory 
description. Not even the locality is known, and may not be in that portion of 
Peru covered by this report. Or it may have originated in that portion of the 
larger viceregal Peru now known as Bolivia. 
111. Pyarprum virratum (Regan) 
Trichomycterus vittatus Regan, 1903, Ann. Mag. Nat. Hist., (7), XII, 623. 
Pygidium vittatum Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, III, 400; 
Eigenmann, 1918c, Mem. Carnegie Mus., VIT, 299. 
Marcapata valley, southeastern Peru 
Only the types are known. Origin of dorsal before vertical from anus, and its 
distance from the caudal one and one half the distance from the snout; anal wholly 
caudal of the vertical from the last dorsal ray; distance of the base of the last anal 
ray from the caudal four and one half times in the total length; caudal truncate; 
dark spots on head and body, and a dark lateral stripe. 
112. PyGiprum pisparR Tschudi 
Pygidium dispar Tschudi, in part, 1845, Fauna Peru., 22, pl. ili, upper figure, High Andes, eastern 
slope, 14,000 feet elevation; 
