472 MEMOIRS OF THE CARNEGIE MUSEUM 



all other Scisenidse by the squamation of the lateral line. (See key to genera.) Here 

 represented by Plagioscion auratus and P. squamosissimus. 



Key to the Guiana Species of Plagioscion. 



n. Second anal spine very large, 2 or 3 in the head auratus. 



aa. Second anal spine short, but little longer than the eye squamosissimus. 



318. Plagioscion auratus (Castelnau). 



Johnius auratus Castelnau, Anim. Am. Sud, Poiss., 1855, 12, pi. 4, fig. 2 (Rio 

 Ucayali). 



Sciama aurata Gunther, Catalogue, II, I860, 287 (copied). 



Plagioscion auratus Jordan and Eigenmann, Rept. U. S. Fish Com. for 1886, 

 1889, 383.— Eigenmann, Proc. U. S. Nat. Mus., XIV, 1891, 67 (rivers of 

 Brazil; name only). — Gosldi, Bol. Mus. Para., II, 1898, 464 (Magoary).— 

 Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 468. 

 One specimen, 175 mm. Georgetown market. (C. M. Cat. No. 2470a.) 

 Head 3.3; depth 3.4; D. X-I,34; A. 11,7; scales 50 with pores, 60 oblique 



series above the lateral line; eye 6 in the head; interorbital wider than the eye, 



4 in the head. 



Compressed; dorsal profile very convex, ventral nearly straight. Head very 



convex above, not spongy; snout bluntish, 4 in the head; maxillary 2.25 in the 



head; mouth large, lower jaw included; teeth of the upper jaw subequal, but larger 



than those of the lower jaw. None of the teeth of the lower enlarged. Gill-rakers 



6 + 12. Scales ctenoid; basal one-third of the soft dorsal scaled. Caudal rhombic; 



pectoral not as long as the ventral; ventral with a filamentous tip reaching to just 



beyond the anus. Second anal spine very strong, 2 in the head. 



Silvery, a little brownish above; most of the spinous dorsal, tips of the soft 



dorsal, and most of the caudal dusky; axil and a small patch on the inside of the 



opercle dusky. 



319. Plagioscion squamosissimus Heckel. 



Plagioscion squamosissimus Heckel, Ann. Wiener Mus., II, 1840, 438. — Reinhardt, 

 Vidensk. Med. Naturhist. For. Kjobenhavn, 1854, 108. — Jordan and Eigen- 

 mann, Rept. U. S. Fish Com. for 1886, 1889, 381 (Obidos; Coary) .—Jordan 

 and Evermann, Bull. U. S. Nat, Mus. No. 47, II, 1898, 1418 (Obidos) .—Eigen- 

 mann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 468. 



Pachyurus squamosissimus Gunther, Catalogue, II, 1860, 526 (copied). 



Scimia squamosissima Steindachner, "Flussfische Sudamerika's, " i, 1879, 3 

 (Amazon; Orinoco; Rio Negro). 



