"It is estimated by very good authority that of the spawn deposited by any fish at a given time not more than 30 per cent. are hatched, and that less than 10 per cent. attain an age when they are able to take care of themselves. As their age increases the chances of reaching maturity become greater and greater. It is among the small residuum of this class that the agency of the bluefish is exercised and whatever reasonable reduction may be made in our estimate, we cannot doubt that they exert a material influence. "The rate of growth of the bluefish is also an evidence of the immense amount of food they must consume. The young fish which first appear along the shores of Vineyard Sound, about the middle of August, are about five inches in length. By the beginning of September, however, they have reached six or seven inches, and on their reappearance in the second year they measure about twelve or fifteen inches. After this they increase in a still more rapid ratio. A fish which passes eastward from Vineyard Sound in the spring weighing five pounds is represented, according to the general impression, by the ten to fifteen-pound fish of the autumn. If this be the fact, the fish of three or four pounds which pass along the coast of North Carolina in March return to it in October weighing ten to fifteen pounds. "As already explained, the relationship of these fish to the other inhabitants of the sea is that of an unmitigated butcher; and it is able to contend successfully with any other species not superior to itself in size. It is not known whether an entire school ever unite in an attack upon a particular object of prey, as is said to be the case with the ferocious fishes of the South American rivers; should they do so, no animal, however large, could withstand their onslaught. "They appear to eat anything that swims of suitable size—fish of all kinds, but perhaps more especially the menhaden, which they seem to follow along the coast, and which they attack with such ferocity as to drive them on the shore, where they are sometimes piled up in windrows to the depth of a foot or more." =The Sergeant-fishes: Rachycentridæ.=—The _Rachycentridæ_, or sergeant-fishes, are large, strong, swift, voracious shore fishes, with large mouths and small teeth, ranging northward from the warm seas. The dorsal spines are short and stout, separate from the fin, and the body is almost cylindrical, somewhat like that of the pike. [Illustration: FIG. 219.—Sergeant-fish, _Rachycentron canadum_ (Linnæus). Virginia. ]