EIGENMANN: the freshwater fishes of BRITISH GUIANA 123 



Key to the Species of Aspredo. 



a. Head to tip of nuchal plate more than 4 in the length to base of caudal aspredo. 



aa. Head to tip of nuchal plate 4 or less in the length to the caudal sicuephorus. 



5. Aspredo aspredo (LinniEus). 

 Silurus aspredo Linn^us, Syst. Nat., ed. 10, 1758, 304; ed. 12, 1766, 502.— Bonna- 



terre, Tabl. Enc. Ichth., 1788, 150.— Lacepede, Hist. Nat. Poiss., V. 1803, 78. 

 Platystacus aspredo Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), II, 



1889, 50 (Para; Arary); Occasional Papers Cal. Acad. Sci., I, 1890, 23. 

 Aspredo aspredo Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 



380; Proc. U. S. Nat. Mus., XIV, 1891, 26. 

 Platystacus Icevis Block, Ausl. Fische, VIII, 1794, 58. — Block and Schneider, S3^st. 



Ichth., 1801, 373. 

 Aspredo la^vis MDller and Trosckel, in Schomburgk, Reisen, Til, 1848, 630 



(Waini). 

 Aspredo batrachus {ex Linnseus, Mus. Adolphi Fred., 1754, 73) Gronow, Cat. Fish, 



ed. Gray, 1854, 137. — Bleeker, " Silures de Suriname," 1864, 93 (Surinam). — 



GtJNTHER, Catalogue, V, 1864, 268, part (British Guiana; Cayenne; Surinam). 



No specimens of this species were secured. It has been recorded from Guiana 

 by Miiller and Troschel and by Giinther. 



Head greatly depressed, spatulate; interorbital width 3.5 in the distance from 

 base of pectoral to tip of snout. Mouth broad, the snout projecting almost its 

 entire length; each jaw with two patches of small teeth. Maxillary barbel reach- 

 ing to base of pectoral, an accessory barbel in front; mental barbel placed near 

 the lip, extending to the post-mental, which is equal to the interorbital. Coracoid 

 processes slightly diverging backward, the length equal to the space between them. 

 A minute pectoral pore at the extremity of the coracoid process. Humeral process 

 a little longer than the coracoid process and overlapping it. 



Distance of dorsal fin from tip of snout 3.8 in the length; first dorsal ray rarely 

 prolonged. Outermost caudal rays slightly produced. Pectoral spine as in A. 

 tibicen. Dorsal surface uniform purplish brown, the ventral surface plain light, 

 shading into light purple or pinkish; dorsal fin dusky, usually with a dusky median 

 stripe on the interradial membrane; caudal dark, except the outermost rays; pec- 

 torals smutty, ventrals usually white, the posterior half sometimes dusky; anal fin 

 white anteriorly, becoming dusky backward; maxillary barbels more or less dusky. 

 Greatest width before pectoral fins 5.66-6 in the length; A. 51-55. 



In the specimens recorded by Cuvier and Valenciennes as Icevis the head is 4 

 or less than 4 in the length to the tip of the caudal. 



