292 MEMOIRS OF THE CARNEGIE MUSEUM. 



ventrals equidistant from snout and tip of caudal, or a little nearer the latter; caudal 

 truncate, or slightly cniarginate; olive above, more or less distinctly spotted with brown; a 

 blackish band from opercle to the caudal; D. S or 9; A. . . . . 5. corduvense (Weyenbergh). 

 cc. Pectoral ray not prolonged; body and head tuberculate; head 6.5-7.5 in the length (with the 

 caudal); eye a little in advance of the middle of the head; maxillary barbel bnjad and short; 

 teeth minute, in many series; 6-S spines in the main row of the interopercle; fins small; 

 posterior part of dorsal over anal; caudal subtruncate or rounded; D. 3 + 8; A. o + 6. 



G. spegazzinii Berg. 



bhb. Back with spots; no lateral baud; maxillary barbel reaching origin of the pectoral or farther; 



distance between origin of dorsal and caudal 2.5-3 in the distance between dorsal and 



snout; origin of ventrals equidistant from snout and tip of caudal. 



d. Pectoral ray not prolonged; head 5.33-5.5; eye in middle of the head, 3 in interorbital; origin 



of anal under end of dorsal; caudal truncate; D. 10; A. 7. Spots of back large, round. 



7. borellii (Houlenger). 



dd. Pectoral ray mucii i)rolonged; head six times in the length; eye entirely in anterior half of 



the head; origin of anal nearly under origin of dorsal; caudal rounded; back, sides, dorsal 



and caudal densely siiotted S. eichorniarum Rilx'iro. 



aa. Teeth in part, at least, incisors; heatl as long as broad; barbels short; first pectoral ray prolonged. 



e. Head S.5 in the length with caudal; eye in anterior half of head, 1.5 in the interorbital; dorsal 

 obliquely truncate, its posterior tliird over the anal; caudal truncate; D. 2 + 9; A. 1 +6; faint 



spots I), riojanum Berg. 



ee. Head six times in the length without the caudal; eye in middle of the head; thirteen spines in the 

 main row of the interopercle; caudal emarginate; D. 4 + C.5; A. 2 + 5.5; nasal barbel extending 

 to posterior margin of the eye 10. heterodontum Eigenmann. 



4. Pygidium tenue'-' (Weyenbergh). (See fig. 7, p. 293.) 

 TrichoNiijcterus tenuis Weyenbergh, Act. Acad. Nac. Cienc. Exact., Cordoba, III, 



1877, p. 12, pi. Ill (Sierra de Cordoba, near C-ruz del Eje); Eigenmann & 



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

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



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



p. 399. 



Habitat. — Rio Primero, Cordoba. 



Yellow, eyes and barbels black; head triangular; opercle and pre-opercle well 

 armed. Body much compressed; D. 6; A. 5. 



5. Pygidium corduvense (Weyenbergh). 

 Trichomyderus corduvensis Weyenbergh, Act. Acad. Nac. Cienc. Exact. Cordoba, 

 III, 1877, p. 11, pi. Ill (Rio Primero); Eigenmann & Eigenmann, Occasional 



" Berg (An. Mus. Nac. Buenos Aires, IV 1895, p. U4) makes this a synonym of Iliiichcrin arcolnta. 

 Boulengcr (Boll. Mus. Zool. Anat.Oomp. Univ. Torino, XII, 1S97), contends that Weyenbergh is right 

 in placing it near P. dispar. 



