Rudder Fish, one of the mackerel family, constituting the only described species of the genus palinurus (De Kay). It belongs to the division of the scomberoids in which the first dorsal is composed of isolated spines connected by a low membrane; the gill covers are serrated and spiny; there are one or more spines in front of the anal fin, which seems to remove it from the scomberoids with which in other respects it agrees; the body is elevated, compressed, and oblong, and the tail without lateral keel; the profile is vertical; the teeth are small, pointed, and nearly equal. The P. per-ciformis (De Kay), the black pilot, or the rudder fish of the fishermen of Martha's Vineyard, attains a length of from 9 to 12 in.; it is occasionally seen on the coasts of Massachusetts and New York. The color is bluish white on the sides, with minute black dots, the lower parts lighter; top of head and back with black blotches; in the young the color is a bright bronzed black, with obscure reddish hues; there are eight short spines in front of the fleshy rays of the dorsal; a bony ridge is observed over the eyes, and there is a depression between them.
Rudder Fish (Palinurus perciformis).