The “flight” of these fish has been compared to that of birds, so as to deceive the observer; however, I cannot perceive any comparison, one being an elegant, fearless, and independent motion, whilst that of the fish is hurried, stiff, and awkward, more like a creature requiring support for a short period, and then its repeated flights are merely another term for leaps. The fish make a rustling noise, very audible when they are near the ship, dart forward, or sometimes take a curve to bring themselves before the wind, and when fatigued fall suddenly into the water. It is not uncommon to see them, when pursued, drop exhausted, rise again almost instantly, proceed a little further, again dipping into the ocean, so continuing for some distance until they are out of sight, so that we remain in ignorance whether they have been captured or have eluded pursuit. The flying-fish swim in shoals, for on one day they are seen rising about, and in the vicinity of the ship, in great numbers; and on the day following, or latter part of the same day, only a few stragglers are seen. When disturbed by the passage of the ship through the shoal, they rise in numbers near the bows of the ship, and the consternation seems to spread among those far distant: the same may be observed when dolphins and albicores are pursuing them. On passing between the islands of Fuego and St. Jago, (Cape Verd group,) in December, 1828, I witnessed a number of bonito in pursuit of flying-fish; the former springing several yards out of the water, in eager chase, whilst large shoals of the latter arose with an audible rustling noise before their pursuers, and the chase continued as far as we could see, a number of victims no doubt being sacrificed to the voracity of their hunters. Besides the finny enemies, they had to encounter, as they rose from the water, boobies, gannets, and tropic birds, which hovered about, and in our view secured very many as they sought refuge in the air. It was a novel sight, and one not often witnessed during repeated voyages, and afforded much amusement and interest to those who beheld it.[14] Occasionally our attention was excited during the voyage, by the remarkable luminosity assumed by the ocean in every direction, like rolling masses of liquid fire, as the waves broke and exhibited an appearance inconceivably grand and beautiful. The phosphoric light, given out by the ocean, exists to a more extensive and brilliant degree in tropical regions, although in high latitudes it is occasionally visible, more especially during the warm months of the year. The cause of it has excited much speculation among naturalists; and although many of the marine molluscous and crustaceous animals, such as _salpa_, _pyrosoma_, _cancer_, several _medusæ_ have been found to occasion it, yet no doubt _debris_, from dead animal matter, with which sea water is usually loaded, is also often one of the exciting causes.