232 MEMOIRS OF THE CARNEGIE MUSEUM 



One specimen, 107 mm. Warraputa. (C. M. Cat. No. 1537a.) 



Five specimens, 25-94 mm. Waratuk. (C. M. Cat. No. 1538a-6; I. U. Cat. 

 No. 11959.) 



Head 2.8-3; depth 4.5-5.2; D. 1,7; A. 1,4; scutes twenty-four or twenty-five, 

 counting the one on the caudal ; four pairs of scutes between the dorsals, nine to 

 eleven plates behind the anal. 



Eye 5-5.5; interorbital 3.5-3.75; mandibular ramus 1.4-1.6 in interorbital; 

 opercle with bristles, curved at their tips, entirely retractile under the opercle, the 

 longest in the adult male a little longer than the eye; margin of snout granular, the 

 granules becoming bristle-like in adult males. Lower surface naked ; supraorbital 

 slightly raised in smaller specimens, head and body otherwise without keels; scutes 

 with numerous spiniferous lines; occipital pointed, bordered by a notched median 

 and two lateral plates. 



Dorsal spine slightly less than head in length; base of dorsal at least equal to 

 its distance from the caudal; ventrals reaching middle of anal; pectoral spine to 

 near middle of ventral or beyond; caudal oblique, emarginate. 



Dark; obscure whitish spots on upper surface; dorsal membrane nearly uni- 

 form, the rays alternately light and dark; caudal with vertical bands, increasing 

 in number with age; upper surface of pectoral and ventral with spots or bars. 



99. Hemiancistrus braueri sp. nov. (Plate XXVIII, figs. 1-2.) 

 Hypostomus itacua (not of Cuvier and Valenciennes), Muller and Troschel, in 



Schomburgk, Reisen, III, 1848, 631 (Takutu). 



Two specimens, 110-120 mm. Guiana (Schomburgk). Berlin Museum 

 No. 3174. The larger one is the type. 



Head 2.8; depth at occiput 4.75; D. 1,8; A. 1,4; plates twenty-seven, count- 

 ing the one on the caudal; five plates between the dorsal fin and the adipose 

 fulcrum; fourteen plates behind the anal, counting all the fulcra; eye 5 in the 

 head, interorbital 3; mandibular ramus 2 in the interorbital. 



Head rather deep; none of the scales carinate; supraorbitals elevate, a distinct 

 median keel on the occipital which is superficially divided into a number of fields; 

 temporal plates not carinate; interopercle armed with about forty slender spines 

 with curved tips, the spines completely revertible, the longest not quite one and 

 one-half times as long as the eye; lower surface of head naked; abdomen with 

 a small patch of plates between the last ventral rays, and a large patch from be- 

 tween the gill-openings to the middle of the pectoral, the rest of the abdomen 

 naked in the type, with minute prickles and a few plates along the middle in the 

 cotype. 



