342 
BULLETIN OF THE BUREAU OF FISHERIES 
with pieces of fish; and at Key West, Fla., where it is known as “turbot,” it is similarly taken in 
company with grunts. 
Its spawning habits and rate of growth, too, are not known. R. L. Barney (field notes) took 
a female on the sea beach of Bogue Banks, Beaufort, N. C., on July 1, 1920, which contained “very 
ripe” spawn. The trigger fish is reported to reach a weight of 4 pounds, but the average is about 
1 pound. 
This fish evidently is rare in Chesapeake Bay, for it was not seen by the field men during the 
present investigation, and we have not seen a record or heard of its previous capture within the 
bay. The specimen at hand was caught with hook and line at the mouth of the Potomac River 
on September 21, 1922, by D. E. Knight, who presented the specimen to the Bureau of Fisheries. 
Habitat . — Both coasts of the tropical Atlantic; on the American coast from Nova Scotia to 
the Dutch West Indies (St. Eustatius, Windward Islands); not common north of Florida. 
Chesapeake records. — (a) Previous records: None. (6) Specimen in collection: From the 
mouth of the Potomac River, Md. 
Family LXXXVIII.-MONACANTHID^E. The filefishes 
Body much compressed, usually quite deep; mouth small, terminal or more or less superior; 
jaws with incisorlike teeth; those of the upper jaw in a double series, in a single series in lower jaw; 
gill openings mere slits; lateral line absent; scales small, bearing spines; first dorsal consisting 
of a single spine (rarely with a second rudimentary spine), smooth or barbed; second dorsal remote 
from the first and similar to the anal; ventrals either absent or represented by a long spine sur- 
mounting the pelvic bone. Two genera and two species of this family of warm-water fishes occur 
in Chesapeake Bay. 
KEY TO THE GENERA 
a. Dorsal spine long and comparatively strong, with two rows of retrorse hooks or barbs posteriorly; 
pelvic bones surmounted by a spine projecting through the skin of the abdomen; gill slit 
short, not longer than eye Monacanthus, p. 342 
aa. Dorsal spine rather weak and comparatively short, without barbs; pelvic bones without 
a spine; gill slits notably longer than eye Ceratacanthus, p. 343 
151. Genus MONACANTHUS (Cuvier) Oken. Foolfishes; Filefishes 
Body short and deep, much compressed; mouth very small, terminal; gill slit oblique, shorter 
than eye; ventral flap and sometimes caudal peduncle spinous; dorsal spine large, posteriorly with 
two series of barbs; second dorsal remote from the spine and similar to the anal, each consisting 
of 25 or more rays; caudal fin broad, round; pectoral fins short and broad; a blunt, movable pelvic 
spine present. A single species comes within the scope of the present work. 
192. Monacanthus hispidus (Linnaeus). Foolfish; Filefish. 
Batistes hispidus Linnseus, Syst. Nat., ed. XII, 1766, p. 405; Carolina. 
Stephanolepis massachuseitensis Uhler and Lugger, 1876, ed. I, p. 90; ed. II, p. 75. 
Monacanthus hispidus Bean, 1891, p. 84; Jordan and Evermann, 1896-1900, p. 1715, PI. CCLIX, fig. 635; Evermann and Hilde- 
brand, 1910, p. 162. 
Head 2.7 to 3.1 (measured to upper angle of gill opening); depth 1.5 to 1.65; D. 1-32 to 34; 
A. 31 to 34. Body short and deep, strongly compressed; profile from snout to dorsal slightly 
concave; snout long, 1.4 to 1.75 in head; eye 2.2 to 3.2; interorbital 3.15 to 3.5; mouth very small, 
terminal; teeth in the jaws broad, with sharp cutting edges; gill opening an oblique slit, situated 
between the eye and the base of dorsal; scales minute, beset with short, rough bristles; first dorsal 
consisting of a single barbed spine inserted over posterior part of eye, remote from second dorsal; 
second dorsal and anal similar and opposite each other, first ray of dorsal sometimes filamentous; 
caudal fin with convex margin; ventral fins represented by a single median spine, extending beyond 
flap of skin attaching the spine to the abdomen; pectoral fins short, 1.95 to 2.2 in head. 
Color variable, grayish or greenish; sides with irregular blackish blotches or with more or less 
definitely horizontally elongated black spots; caudal fin often dusky; other fins plain translucent. 
