164 MEMOIRS OF THE CARNEGIE MUSEUM 



Six specimens, 107-184 mm. Yackeatonuk Fall, Potaro River. (C. M. Cat. 

 No. 1596a-6; I. U. Cat. No. 12001.) 



Eight specimens, 86-168 mm. Nickaparu Creek. (C. M. Cat. No. 1604a-c; 

 I. U. Cat. No. 12002.) 



Fifteen specimens, 80-219 mm. Guiana, label not legible, collected by Indians 

 in the upper Potaro or upper Rupununi. (C. M. Cat. No. 1605a-e; I. U. Cat. 

 No. 12005.) 



One specimen, 215 mm. Potaro Landing. (C. M. Cat. No. 1597a.) 



Thirteen specimens, 78-164 mm. Holmia, creeks. (C. M. Cat. No. 1598a-e; 

 I. U. Cat. No. 12003.) 



Three specimens, 205-242 mm. Chipoo Creek, branch of the Ireng. (C. M. 

 Cat. No. 1599a; I. U. Cat. No. 12004.) 



This species inhabits the plateaus of Guiana. It has not been recorded from 

 Guiana before. It is very closely allied to seha', from which it differs principally 

 in its longer maxillary barbel. 



Head 4.16-4.5; depth 5-4.3; D. 1,6; A. 11. 



Head about an orbital diameter longer than broad; eye in middle of head, 6.5 

 in head in adult, 2.5 in interorbital; maxillary barbel reaching middle of adipose 

 in the young, not to middle in the old; outer or post-mental barbel not reaching 

 beyond pectoral; dorsal spine equaling snout in adult; pectoral spine a little 

 longer; spines shorter in the young; adipose fin half of the length without the head; 

 caudal cleft to its base, the upper lobe narrower, both lobes rounded, equal to the 

 head. Ashy above, blotched with darker; base of dorsal opaque at base, then 

 hj^aline, darker above; other fins uniform. 



40. Rhamdia sebae (Cuvier and Valenciennes) . 



"Rhamdia ou bagre de rio " Marcgrave, Hist. Rer. Nat. Bras., IV, 1648, 149. 



Seba, Locupl. Rer. Nat. Thes. Ace. Descr., Ill, 1748, pi. 29, fig. 5. 



" Mystus " No. 83, Gronow, Mus. Ichth., 1, 1754, 34; No. 384, Zoophyl., 1763, 125. 



Pim.elodus seboe Cuvier and Valenciennes, Hist. Nat. Poiss., XV, 1840, 169 

 (Surinam; Cayenne; Rio Janeiro; Buenos Aires). — MUller and Troschel, 

 in Schomburgk, Reisen, III, 1848, 628 (all Guiana rivers). — Hyrtl, Denkschr. 

 Akad. Wiss. Wien, XVI, 1859, 16 (vertebra; 11 + 2 + 26).~Quoy and 

 Gaimard, Voy. Uranie et Physicienne, ZooL, 1824, 228, pi. 49, figs. 3 and 4. — 

 GuNTHER, Catalogue, V, 1864, 119 (Demerara; British Guiana; Brazil). 



Pimelodus (Rhamdia) sebce Steindachner, " Siisswasserfische Siidostlichen 

 Brasilien," iii, 1876, 68 (Demerara; Essequibo; St. Martha, mouth of 



