EIGENMANN: the PYGIDIID^, a family of south AMERICAN CATFISHES. 291 



Pygidium marmoralum Eigenmann & Eigenmann, Proc. U. S. Nat. Mus., XIV, 

 1891, p. 36; Eigenmann, Reports Princeton Univ. Exped. Patagonia, III, 

 1910, p. 399. 

 Habitat. — Chile. 



Blackish gray, marbled with many black spots, as in pundatum; fins dark. 

 Depth 10.82;D. 10; A. 6. 



2. Pygidium palleum (PhiHppi.) 



Trichomycterus palleus Philippi, Mb. Ak. Wiss. Berlin, 1866, p. 715; Eigenmann & 



Eigenmann, Occasional Papers Cal. Acad. Sci., I, 1891, p. 325; Delfin, 



Catalogo de los Feces de Chile, 1901, p. 30. 

 Pygidium palleum Eigenmann & Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 



p. 36; Eigenmann, Reports Princeton Univ. Exped. Patagonia, III, 1910, p. 



399. 



Habitat. — Chile. 



Light reddish; fins colorless; head 6.5 in total; D. 9-10; A. 6. 



3. Pygidium tigrinum (Philippi). 



Trichomycterus tigrinum Philippi, Mb. Ak. Wiss. Berlin, 1866, p. 714; Eigenmann 



& Eigenmann, Occasional Papers Cal. Acad. Sci., I, 1890, p. 326; Delfin, 



Catalogo de los Peces de Chile, 1901, p. 31. 

 Pygidium tigrinum Eigenmann & Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 



p. 36; Eigenmann, Reports Princeton Univ. Exped. Patagonia, III, 1910, 



p. 399. 



Habitat. — Chile. 



Light with reddish points; fins immaculate; head 6.5; depth 6.5 in total length; 



D. 9 or 10; A. 6. 



Members of the genus Pygidium have been recorded from the mountains of 

 Argentina, north of the latitude of Buenos Aires. South of this latitude species 

 of Hatcheria take their place. 



Key to the species of Pygidium from Argentina and the Paraguay Basin 



a. Teeth pointed (not examined in tenue). 



b. Plain yellowish, eyes and barbels black; head triangular; opercle and pre-opercle well armed; 



body much compressed; D. 6; A. 5 4. tenue (Weyenbergh). 



66. Back spotted, sides with a band. 



c. Pectoral ray prolonged; head as wide as long, 4.66-5 in the length; eye very small, a little in 

 advance of middle of head, its diameter three in the interorbital; maxillary barbel reaching 

 pectoral; depth of caudal peduncle half its length; origin of dorsal behind the ventrals, 

 its distance from the caudal two and one-half in its distance from the snout; origin of 



