22 CALIFORNIA ACADEMY OF SCIENCES. 



Silurus coiylephorus Lacepede, Syst. Ichthyol. v, 78, 1803. 

 Aspredo cotyloj^herus Giiuther, Cat. Fish. Brit. Mus. v, 269, 1864,, 



(Surinam). 

 Silurus hexadactylus LacepMel. c. 82. 

 Aspredo sex-cirrhis Cxiv. & Val., Hist. Nat. Poiss. xv, 441, 1840 



(Surinam); Kner, SB. Ak. Wien, xvii, 1855, 93 (Surinam). 

 Aspredo spiectrum Gronow, "Syst. Ichthyol. 137, 1854." 

 Habitat: Surinam and Bio Para. 



Head greatly depressed, narrowed forward; interorbital 

 width 3^ in the distance from base of pectoral to tip of 

 snout; width of mouth equals the interorbital plus the 

 orbits, the snout projecting half its length. Inter- 

 inaxillaries with 2 rhomboidal patches of villiform teeth, 

 lower jaw with wider patches of similar teeth. 



Maxillary barbels reaching to gill-opening, mental 

 not to postmental barbels which are as long as width of 

 mouth. 



Coracoid processes slightly diverging backward, the 

 length of the processes 11 in the distance between their 

 bases. Humeral processes co-extensive with but not 

 overlapping the coracoid processes. 



Pectoral pore below the tip of humeral process. 



Distance of dorsal fin from tip of snout 3|-3| in the 

 length; first dorsal ray scarcely prolonged. 



Outermost caudal rays prolonged. Four rows of 

 papillae on the sides. 



Color uniform dark brown in some specimens, pro- 

 fusely mottled with lighter in others; one example is 

 abruptly lighter behind the dorsal fin, another has the 

 dorsal surface of head and nape to the dorsal fin plain 

 light, with marblings of light on the brown ground 

 posteriorly; fins uniform brown, or mottled like the 

 body or the anal, sometimes white anteriorly. 



A. 53-57; greatest width, before pectoral spine, 5|; 

 length of head to gill opening 9 in the length, with the 

 caudal fin. 



Nine specimens .14-. 33 m. Vigia; Para; Tajapuru. 

 Thayer Exped. 



