HISTORY OF THE FISHES OF MASSACHUSETTS. 493 
GENUS I. MONACANTHUS, Cov. 
Body covered with very small scales, bristling with stiff excrescences, and ex- 
tremely crowded. The extremity of the pelvis projecting and spiny, as in the 
Balistes, but they have only one large dentated spine to their first dorsal, or at 
least the second is almost imperceptible. 
MoNACANTHUS AURANTIACUS, Dekay. 
The Orange File-fish. 
(PLaTE XXXIV. Fra. 3.) 
Balistes aurantiacus, Orange File-fish, Mrrcn., Trans. Lit. and Phil. Soc. of N. Y., 1. p. 468, pl. 6, fig. 1. 
Monacanthus aurantiacus, Orange File-fish; Dexay, Report, p. 333, pl. 57, fig. 186. 
n wid STORER, Proceed. Bost. Soc. Nat. Hist., 11. p. 72. 
- a * Mem. Amer. Acad., New Series, 11. p. 496. 
= X S Synopsis, p. 244. 
Color. The greater portion of the fish is of an orange-yellow ; the lower portion 
of the sides and beneath of a bluish-white. 
Description. Body oval, compressed. Its entire surface covered by minute prickles, 
which are very obvious when the hand is drawn towards the head. Abdomen tumid. 
A slight concavity is noticed upon the forehead; the dorsal outline is horizontal. 
The greatest depth of the fish is just back of the pectorals. The length of the 
head is equal to about one quarter its entire length. The mouth is small, promi- 
nent, protruding. The lower jaw the longer, with eight flattened teeth; the front 
teeth large, flattened, emarginated above; the teeth in the lower jaw smaller and 
lanceolate. The eyes are large and circular, situated just beneath the dorsal spine. 
The branchial aperture, which is linear and nearly as long as the dorsal spine, is 
situated just beneath the eye. The nearly straight dorsal spine is equal to one half 
the length of the head; it is slightly rounded on its anterior edge, grooved at its 
posterior base, and exhibits numerous very minute serrations upon its posterior 
superior edge. A small membrane is attached to its base, posteriorly. 
Just before the second dorsal fin, which commences on a line slightly anterior 
to the anal, is a prominent projection. This fin is rounded above. The middle rays 
are the longest; all the rays are more or less flattened. 
The pectorals are broad and rounded, and situated on a line directly beneath 
the eyes. 
