FISHES OF CHESAPEAKE BAY 
199 
This species is distinguished from S. guachancho (the only other species of the genus recorded 
from waters north of Florida) principally by the smaller scales, the more posterior position of the 
ventral fins with reference to the spinous dorsal, and by the smaller mouth. A comparison of these 
characters is presented in the key to the species. 
This is the smallest of the barracudas, rarely reaching a length of more than 1 foot. It has 
been called the Northern barracuda because it was thought to be entirely of northern distribution, 
its range having only recently been found to extend into the Tropics. 
Habitat . — Cape Cod to Panama. 
Chesapeake localities — (a) Previous records: Cape Charles city, Va. (6) Specimens in col- 
lection: None. 
Family XLVIII.-PQIYNEMID&. The threadfins 
Body oblong, compressed; snout conical, projecting beyond mouth; eye anteriorly placed, with 
a well-developed adipose eyelid; mouth large, nearly horizontal; teeth in villiform bands on jaws, 
palatines, and sometimes on vomer; gills 4, a slit behind the fourth; branchiostegals 7; lateral line 
complete, continued on caudal fin; dorsal fins 2, rather remote from each other, the first with 7 or 
•Y-:' 
Jit 
8 rather high, feeble spines; caudal fin deeply forked; anal fin either similar to second dorsal or much 
longer; ventral fins abdominal, with I, 5 rays; pectoral fins placed low, in two parts, the lower part 
consisting of free articulated filaments. 
75. Genus POLYNEMUS Linnseus 
Vomer with teeth; preopercle serrate, its lower posterior angle with a scaly flap; anal fin not 
much longer than second dorsal, consisting of about 13 or 14 rays; pectorals with 3 to 9 free fila- 
ments, all shorter than body. A single species was taken in Chesapeake Bay. 
100. Polynemus octonemus Girard. Threadfin. 
Polynemus octonemus Girard, Proc., Ac. Nat. Sci., Phila., 1858, p. 167; Brazos, Santiago, and Galveston. 
Ploydactylus octonemus Jordan and Evermann, 1896-1900, p. 830, PI. CXXVIII, fig. 350. 
Head 3.25 to 3.4; depth 3.1 to 3.35; D. VIII-I, 12; A. Ill, 13; scales about 58 (most of the 
scales are lost in specimens at hand). A fairly accurate count, however, is obtainable from one 
specimen, which gives the result stated when counting oblique series running upward and back- 
ward above lateral line. Jordan and Evermann (1906, p. 830) give 70 scales in a lateral series. It 
is probable that these authors started counting the series from the nape. Gill (1860, p. 280) states 
that the lateral line runs through 60 scales. Body compressed; caudal peduncle rather strongly com- 
pressed, deep, 2.2 in head; head moderate, compressed; snout conical, projecting far beyond mouth, 
its length 5.3 to 5.55 in head; eye 4.75; interorbital 4 to 4.3; mouth moderate, inferior, horizontal; 
maxillary broad, 2.35 to 2.45 in head; teeth small, in villiform bands on jaws, vomer, and palatines; 
49826—28 -14 
XX / 
