356 MEMOIRS OF THE CARNEGIE MUSEUM 



aa. Scales 41, usually fewer. 



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



bimaculatus. 

 dd. Anal emarpnate, a black band across the ba.se of the caudal potaroensis. 



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

 Tetrago7iopterus 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. 

 Poecilurichthys 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-j; 

 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 yoimg; D. 11; A. 27-31^'; 

 scales 10-42 to 46«-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. 



Occii^ital 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 



" Gunther gives the anal as 34 in the type. In (wcnty specimens examined two have 27 rays, four have 

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



■'* In sixteen six have 42, six have 43, two have 44, one has 45 and one 46. 



