THE SHORE FISHES OF PERU 49 



Genus DISCOPYGE Tschudi, 1846 



Disk more or less circular, about half the total length; electric 

 organs present; a cartilaginous support extending forward from mter- 

 orbital ridge; mouth small; teeth in pavement; spu-acles close behind 

 eyes; skin smooth; tail depressed, with lateral folds, and two dorsal 

 fins of about equal size, and a rather broad caudal fin; ventral fins 

 united by membrane across the tail, or at least attached to the tail, 

 wherein this genus differs chiefly from Narcine. 



A single species is recorded from Peru. 



DISCOPYGE TSCHUDII Heckel 



Discopyge tschudii Heckel, in Tschudi, 1845, p. 33, pi. 6, Heradura, between 

 Huacho and Chancay, Peru (original description). — Abbott, 1899, p. 329 

 (original description republished).— Norman, 1937, p. 11, fig. 3, 46°18'15" S., 

 65°02'15" W., Buenos Aires, A^rgentina, and Coronel, Chile. — Fowler. 

 1941a, p. 225 (references). 



Disk very nearly as wide - long, its anterior outline broadly 

 rounded; its width 2.0 in total length; its length 1.95; its length 

 anterior to axil of pectoral 2.1; length anterior to vent 2.0; length 

 posterior to vent 2.05; tail moderately depressed, its width at axil of 

 ventrals 6.2 in length anterior to vent; its depth at same place 12.0; 

 depth of its peduncle 4.3 in snout; with a very prominent lateral 

 dermal fold, beginning about under origin of first dorsal; snout 

 fairly long, its length anterior to eye 4.0 in length anterior to vent; its 

 preoral length 3.7; rostral cartilaginous supports extending forward 

 from interorbital ridges slightly divergent; eye very small, notably 

 smaller than spiracle, the former 6.85 in snout anterior to eye; inter- 

 spiracular space broad, 1.6; mouth small, its width 3.7 in snout 

 anterior to eye; teeth transversely elongate, each tooth with a point 

 posteriorly, rather larger and sharper on the posterior teeth than the 

 anterior ones; the two dorsal fins nearly of same shape and size, 

 the base of the second one 2.1 in snout, and its height 1.9; space 

 between dorsal fins 4.3 ; caudal fin rather broad, with obliquely rounded 

 margin, the upper part being longer than the lower; ventral with a 

 very broad, gently convex distal margin, its outer margin 4.0 in 

 length anterior to vent; claspers about a fourth longer than adjacent 

 parts of ventrals, 4.5 in length anterior to vent. 



Color above brown; the numerous pores appearing as pale specks; 

 plain pale underneath. 



The foregoing description is based on a male, 390 mm. long, from 

 "Argentina," which seems to agree well with the origmal description. 

 Only the specimen on which the original description was based is 

 known from Peru. 



Range. — Southward from about the middle of Peru, and apparently 

 on the Atlantic to the Rio de la Plata. 



