EIGENMANN: THE PYGIDIIDzE, A FAMILY OF SOUTH AMERICAN CATFISHES. 301 



Pygidium taczanowskii Eigenmann & Eigenmann, Proc. Cal. Acad. Sci. (2), 



II, 1889, p. 52; Occasional Papers Cal. Acad. Sci., I, 1890, p. 338; Proc. U. S. 

 Nat. Mus., XIV, p. 37; Eigenmann, Reports Princeton Univ. Exped. Patagonia, 



III, 1910, p. 400. 



Habitat. — North and central Peru, between the Andes. 



Head in specimens 110-113 mm. 5-5.5; in a specimen 390 mm. 4.75; I). 9-10; 

 A. 7; P. 9; width of head 1.2 in its length, snout 2-2.33; interorbital 3-3.33, nasal 

 barbels 1-1.25 in the head, in small specimens, 1.4 in larger specimens, maxillary 

 barbels 1.21-1.25, lower barbels 1.6-2; width of mouth two times in the length of 

 the head; anterior margin of eye slightly in front of the middle of the head in smaller 

 individuals, in the middle in the larger; teeth brush-like; opercular and interoper- 

 cular spines numerous, in several series, mostly concealed; origin of dorsal variable 1 , 

 moving back with age, in a specimen 110 mm. its origin much nearer gill-opening 

 than to caudal; in specimens 390 mm. 1.22 nearer middle caudal rays than tip of 

 opercle; origin of ventrals in specimens up to 210 mm. almost directly under the 

 origin of the dorsal, in a specimen 390 mm. half the length of the head farther 

 forward; the origin of the anal in front of the end of the dorsal in small specimens, 

 under it in the specimen 390 mm. long; first pectoral ray prolonged, its length 1-1.37 

 in the length of the head. Without spots, bands, or stripes. 



17. Pygidium rivulatum (Ouvier & Valenciennes). (Plate XLV, figs. 2, 3.) 



Trichomycterus rivulatus Cuvier & Valenciennes, Hist. Nat. Poiss., XVIII, 

 1846, p. 495 (Guasacona); Gunther, Cat. Fishes Brit. Mus., V, 1864; Cope, 

 Proc. Amer. Philos. Soc, XVII, 1877, p. 46 (Lake Titicaca); Pellegrin, 

 Bull. Soc. Zool. Paris, XXIX, 1904, p. 91; Poissons des Lacs des Hauts 

 Plateaux, de l'Am. Sud., 1907, p. 17 (Rio de Pazna, lac Poopo). 



Pygidium rivulatum Eigenmann & Eigenmann, Proc. Cal. Acad. Sci. i'l), II, 1889, 

 p. 51 (Cuzco; Moho and Puno, Lake Titicaca); Occasional Papers Cal. Acad. 

 Sci., I, 1890, p. 330, Proc. U. S. N. Mus., XIV, 1891, p. 36; Stauks, Proc. 1". S. 

 N. Mus., XXX, 1907, p. 771 (Lake Titicaca); Eigenmann, Reports Princeton 

 Univ. Exjied. Patagonia, III, 1910, p. 399. 



? Trichomycterus inccc Cuvier & Valenciennes, /. c, 496 (Rio Guatanai at Cuzco). 



Trichomycterus gracilis Cuvier & Valenciennes, I. c, 497 (Rio Azangaro near 

 Guasacona; Rio Guatanai near Cuzco; Rio Pontezualo near Coroico; Lake 

 Compucila near Cuzco); Cope, Proc. Amer. Philos. Soc. XVII, 681, 1877 

 (Tinta). 



Trichomycterus barbatula Cuvier & Valenciennes, /. c, 498 (Guasacona; Rio 

 Pontezualo near Coroico). 



