_Rachycentron canadum_, called cobia, crab-eater, snooks, or sergeant-fish, reaches a length of about five feet. The last name is supposed to allude to the black stripe along its side, like the stripe on a sergeant's trousers. It is rather common in summer along our Atlantic coast as far as Cape Cod, especially in Chesapeake Bay. _Rachycentron pondicerrianum_, equally voracious, extends its summer depredations as far as Japan. The more familiar name for these fishes, _Elacate_, is of later date than _Rachycentron_. Mr. Prime thus speaks of the crab-eater as a game-fish: "In shape he may be roughly likened to the great northern pike, with a similar head, flattened on the forehead. He is dark green on the back, growing lighter on the sides, but the distinguishing characteristic is a broad, dark collar over the neck, from which two black stripes or straps, parting on the shoulders, extend, one on each side, to the tail. He looks as if harnessed with a pair of traces, and his behavior on a fly-rod is that of a wild horse. The first one that I struck, in the brackish water of Hillsborough River at Tampa, gave me a hitherto unknown sensation. The tremendous rush was not unfamiliar, but when the fierce fellow took the top of the water and went along lashing it with his tail, swift as a bullet, then descended, and with a short, sharp, electric shock left the line to come home free, I was for an instant confounded. It was all over in ten seconds. Nearly every fish that I struck after this behaved in the same way, and after I had got 'the hang of them' I took a great many." =The Butter-fishes: Stromateidæ.=—The butter-fishes (_Stromateidæ_) form a large group of small fishes with short, compressed bodies, smooth scales, feeble spines, the vertebræ in increased number and especially characterized by the presence of a series of tooth-like processes in the œsophagus behind the pharyngeals. The ventral fins present in the young are often lost in the process of development. According to Mr. Regan, the pelvic bones are very loosely attached to the shoulder-girdle as in the extinct genera _Platycormus_ and _Homosoma_. This is perhaps a primitive feature, indicating the line of descent of these fishes from berycoid forms. We unite with the _Stromateidæ_ the groups or families of _Centrolophidæ_ and _Nomeidæ_, knowing no characters by which to separate them.