140 MEMOIRS OF THE CARNEGIE MUSEUM 



Barima).— Kner, SB. Akad. Wiss. Wien, XXVI, 1857, 384, pi. 1, fig. 2 (Para). 

 Arius mesops Gunther, Catalogue, V, 1864, 145 (copied). 

 Galeichthys mesops Jordan, Proc. U. S. Nat. Mus., IX, 1886, 559 (name only). 

 Tachisurus mesops Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 1888, 



141 (name only); Occasional Papers Cal. Acad. Sci., I, 1890, 57. 

 Sciadeichthys mesops Jordan and Evermann, Bull. U. S. Nat. Mus. No. 47, I, 



1896, 123. 

 Bagrus coelestinus Muller and Troschel, Horse Ichth., Ill, 1849, 7 (Guiana).— 



Muller and Troschel, in Schomburgk, Reisen, III, 1848, 627 (Waini and 



Barima) . 

 Hexanematichthys hymenorhinus Bleeker, Versl. en Med. Akad. Wet. Amsterdam, 



XIV, 1862,377 (Surinam); " Silures de Suriname," 1864, 57, pi. 11, fig. 2, 



pi. 13, fig. 4 (Surinam). 

 Netuma dubia Bleeker, Versl. en Med. Akad. Wet. Amsterdam, XIV, 1862, 382 



(Surinam); ''Silures de Suriname," 1864, 63, pi. 15, fig. 2, pi. 13, fig. 5 



(Surinam). 

 Arius dubius Gunther, Catalogue, V, 1864, 144 (copied). 

 Galeichthys dubius Jordan, Proc. U. S. Nat. Mus., IX, 1886, 559 (name only). 

 Tachisurus dubius Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 



1888, 141 (name only). 



Many specimens, 230-335 mm. Georgetown market. (C. M. Cat. No. 1266- 

 1269; I. U. Cat. No. 11776.) 



Several specimens, to 197 mm. Mahaica. (C. M. Cat. No. 1733). 



Head 3.66-3.75; depth 5-6; D. 1,7; A. 18. Eye 1.75-2.5 in snout, 2.33-4 in 

 interorbital, 5.5-8 in head. 



Elongate, the width equal to or greater than the depth. Width of the head 

 1.25-1.33 in its length, at the angle of the mouth about 2; its depth 1.66-1.75 in its 

 length. Humeral process, dorsal plate, and top of head to between the eyes, granular. 

 Occipital process wider than long, scarcely keeled. Fontanel not continued behind 

 the eyes and without backward projecting groove. Posterior nares connected by a 

 membrane. 



Barbels flattish, those of the maxillary reaching to near the ventrals (to middle 

 of pectorals in older individuals) ; post-mental to or beyond base of pectoral, mental 

 to gill-opening. Teeth villiform, vomerine and palatine patches of about equal 

 size and shape in the young, a separate patch behind the palatines being developed 

 sooner or later. The teeth of the palate differ more than in any other species. 



Gill-membranes meeting in an angle, forming a fold across the isthmus. Gill- 

 rakers 6 + 10. 



