In reference to these same flying-fish, the species washed on board the ‘Parana’ by the waves of the turbulent Atlantic, and that found their way into the stomach of a dolphin of terrestrial habits, was _Exocetus exiliens_. I could see nothing of its movements, as the sea simply washed it into the sponsons, or left it floundering on the deck. Its general appearance was exactly like a newly-caught herring: the scales, thin and rounded, easily detached, and adhered to the hand; the back a light steel-blue, with greenish reflections, shading into silvery whiteness on the sides; the pectoral fins reached quite to the tail, and were shaped like the wings of a swift; the dorsal and anal fins are opposite each other, and placed near the tail, which is deeply but unevenly forked—the lower limb being much the longer; the ventral fins, which are posterior to the middle of the body, are unusually long and strongly rayed. But in the uncomfortably calm Pacific, where I watched the flying-fish every day, and often all day long, I had ample opportunity to observe its so-called ‘flying.’ The species that tenant the two oceans are very nearly allied, _Exocetus volitans_ being the one common to the Pacific; but it is of habits I wish to treat, not of minute specific distinctions—that can be settled in the studio. It seems to me that the distance traversed when the fish leaps from the sea, and the length of time it remains out of the water, are much overestimated in books on Natural History. Ten or twelve seconds may be taken as the average time of its flight, and eighty yards the maximum distance traversed when the water is perfectly tranquil; if aided by a breeze of wind, or propelled from the crest of a breaker, the distance accomplished would necessarily be greater; but the fins have no power to raise the fish a single inch above the level of its leap, and simply aid in its support, as the extended skin of the flying-squirrel bears it up in its spring from bough to bough. I have never seen the fins vibrated or flapped, as all wings invariably are, but, stiff and rigid, are extended and still, until the fish plunges into the sea. Numbers, beyond all computation, were constantly seen by us in the air together, when chased by predatory fish. The flying-fish, as a rule, is about twelve inches in length.