PISHES OP CHESAPEAKE BAY 
269 
Family LXVII.-KYPHOSID/E. The rudder fishes 
Body elongate or ovate, compressed; head rather short; mouth small or moderate; outer 
teeth in jaws incisorlike, no molars; opercle entire; gill membranes free from the isthmus; the 
rakers rather long; gills 4, a slit behind the fourth; pseudobranchi® well developed; scales small 
or moderate; dorsal fin continuous or divided, with 10 to 15 spines; anal fin with three spines; 
ventral fins thoracic, with I, 5 rays and an accessory scale at base; pectoral fin without spine. 
117. Genus KYPHOSUS Lacepede. Rudder fishes 
Body ovate or elongate; head short; snout blunt; mouth small; jaws with a row of incisor 
teeth and a narrow band of villiform teeth behind them; fine teeth present on vomer, palatines, and 
tongue; branchiostegals 7; lateral line continuous, present on base of caudal; scales moderate or 
small, ctenoid, covering most of head, vertical fins, and sometimes most of the paired fins; dorsal fin 
long, continuous, with 11 spines of irregular length, depressible in a groove; caudal fin forked; anal fin 
with three spines, the soft part similar to that of dorsal; ventral fins inserted behind pectorals. 
149. Kyphosus sectatrix (Linnaeus). Rudder fish. 
Perea sectatrix Linnaeus, Syst. Nat., ed. XII, 1766, p. 486. 
Kyphosus sectatrix Jordan and Evermann, 1896-1900, p. 1387, PI. CCXIX, fig. 559. 
Head 2.8 to 3.5; depth 2.1 to 2.4; D. XI, 12 to 14; A. Ill, 11 to 13; scales 58 to 64. Body moder- 
ately deep, compressed; back elevated; head rather short, snout blunt, 3.1 to 4.15 in head; eye 2.6 
to 3.1; interorbital 2.8; mouth moderate; upper jaw slightly projecting; maxillary reaching to or a 
little beyond eye, 2.9 to 3.3 in head; gill rakers rather slender, about 15 on lower limb of first arch; 
teeth incisorlike; scales moderate, ctenoid, anteriorly notably larger below the lateral line than 
above it; small scales covering vertical fins in adult; dorsal fin continuous, rather low, its origin 
slightly behind base of pectorals; caudal fin deeply emarginate to slightly forked; anal fin with three 
short spines, the soft part similar to that of dorsal; ventral fins inserted under origin of dorsal; 
pectoral fins short, 1.55 to 1.8 in head. 
Color of adult in alcohol uniform dark brown; a faint pale streak below eye; a black margin 
on opercle above posterior angle. Young irregularly mottled with dark and pale areas. 
A single small specimen, 32 millimeters in length, occurs in the Chesapeake collection. The 
foregoing description is based on this fish and 10 others from Beaufort, N. C., ranging in length 
from 33 to 130 millimeters (1)4 to 5 inches). This is a fish principally of tropical waters. It has 
not been recorded previously from Chesapeake Bay, although stragglers have been caught as far 
north as Massachusetts. 
The rudder fish is said to be a good food fish and to possess game qualities. It receives its 
common name from the habit of following vessels, presumably for waste foods thrown overboard. 
Four specimens taken at Beaufort and examined by Linton had fed on crabs, small bivalve shells, 
and vegetable debris. The species is reported to be one of the leading food fishes in the Bermudas. 
It is not common at Key West, Fla., and apparently rather rare on the coast of the Isthmus of 
Panama. The maximum recorded weight is 9 pounds. 
Habitat . — Massachusetts to Panama, occurring only as a straggler from North Carolina 
northward. 
Chesapeake localities. — (a) Previous records: None. (5) Specimen in collection: From 
Fisherman’s Island, Va., caught on July 23, 1916, in a tow net. 
Family LXVIII. — GERRID/E. The mojarras 
Body oblong or elongate, compressed; mouth small, extremely protractile, descending down- 
ward when protruded; a deep groove in upper surface of snout, receiving the long spine of the pre- 
maxillary; supplemental maxillary bone wanting; teeth in jaws small, in bands, none on vomer or 
palatines; gill membranes separate, free from the isthmus; scales rather large, cycloid; dorsal fin 
single, the spinous and soft parts about equally developed, usually with 9 or 10 spines; anal fin much 
shorter than the dorsal, with two or three spines; ventral fins thoracic, with I, 5 rays; air bladder 
present. A single genus of this family of tropical fishes comes within the scope of the present work. 
