356 MEMOIRS OF THE CARNEGIE MUSEUM 



aa. Scales 41, usually fewer. 



</. Anal margin straight; a black stripe on the caudal peduncle, continued on the middle rays. 



bimaculatus. 

 dd. Anal emarginate, a black band across the base of the caudal potaroensis. 



216. Pcecilurichthys polylepis (Giinther). (Plate LII, figs. 2, 3.) 

 Tetragonopterus maculatus Muller and Troschel, Horse Ichth., I, 1845, 74, part; 



in Schomburgk, Reisen, III, 1848, 634, part. 

 Tetragonopterus polylepis Gunther, Catalogue, V, 1864, 320 (British Guiana). 

 — Eigenmann and Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 52.— 



Ulrey, Ann. N. Y. Acad. Sci., VIII, 1895, 276. 

 Pcecilurichthys polylepis Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 



1910, 433. 



One specimen, 44 mm. Wismar. (C. M. Cat. No. 1416a.) 



Nineteen specimens, 35-53 mm. Rockstone. (C. M. Cat. No. 1418a-d; 

 I. U. Cat. No. 11789.) 



Ten specimens, 38-52 mm. Gluck Island. (C. M. Cat. No. 1417a-c; I. U. 

 Cat. No. 11790.) 



Ten specimens, 49-85 mm. Crab Falls. (C. M. Cat. No. 1415a-c; I. U. 

 Cat. No. 11791.) 



Sixty-nine specimens, 50-85 mm. Tumatumari. (C. M. Cat. No. 1419a-,?; 

 I. U. Cat. No. 11792.) 



Readily distinguished by its circular spot over the seventh to ninth scales of 

 the lateral line, and by its small scales. 



Head 3.5-4; depth 2 in the largest to 2.5 in the young; D. 11; A. 27-31 47 ; 

 scales 10-42 to 46 4S -7 to 9 to ventrals; eye 3; interorbital 2.3. 



Much compressed, very deep in the old, the ventral profile pendant; dorsal 

 profile regularly arched from the snout to the caudal peduncle; much slenderer 

 in the young, but maintaining the same ratio of curvature between back and belly. 

 Preventral region narrowly rounded, the pectorals considerably above the lower 

 edge of the breast; scales of belly irregularly imbricate; postventral area narrowly 

 compressed; entire back very narrow, not especially keeled. Predorsal area naked 

 to near the dorsal, where there are a few median scales or a few of the scales of one 

 side overlapping the back. 



Occipital process one-fourth of the distance from its base to the dorsal, bor- 

 dered on the sides by five scales; skull smooth, very convex; frontal fontanel shorter 



" ( liinther gives the anal as 3 1 in the type. In twenty specimens examined two have 27 rays, four have 

 28, eight have 29, four have 30 and two have 31. 



18 In sixteen six have 42, six have 43, two have 44, one has 45 and one 4(3. 



