I have never seen these animals emitting light, but it is well known that many phosphorescent animalcules shine only in certain stages of the weather or at certain seasons of the year: and as several distinguished travellers have spoken of their luminous properties, it is at least probable that they or their congeners act an important part in dramas similar to that which has been just described. At all events, their history clearly shows the vastness of the scale of animal existence in the superficial waters of the ocean. But for the little yellow spot within their bodies, they would be totally invisible at the distance of a few feet in their native fluid, and could not interfere appreciably with the progress of the rays of light. If further proof were necessary to show the incalculable increase of many oceanic tribes, it might be found in the history of living beings much more familiar to the mariner. Most persons have met with notices of the Portuguese man-of-war, called, by naturalists _physalia_, a living air sac of jelly provided with a sail, armed with a multitude of dependant bottle shaped stomachs, all capable of seizing prey, and colored more beautifully than the rainbow. This splendid creature pursues its way over the waves with all the skill of an accomplished pilot, and furnishes, when caught, one of the most astonishing examples of the adaptation of animal structure to the peculiar wants, and theatre of action of living beings, one of the most striking evidences of Omniscient Wisdom which nature offers to the moralist. The physalia rarely sails in squadrons, but wanders solitary and self-dependent over the tropical seas, a terror even to man, by the power which it possesses of stinging and inflicting pain upon whatever comes in contact with its long, trailing cables. But there is another little sailor called the _velella_; unprovided with offensive weapons, though formed in most respects upon a model somewhat similar to that of the physalia, unguarded as the peaceful trader against the piratical attacks of a thousand enemies, its very race would soon become extinct, were it not for its unlimited increase. Provided with a flat, transparent, oval scale of cartilage, for the support of a gelatinous body, it floats by specific levity, alone, for it has no air vessel—and employs its hundreds of stomachs for ballast. Another scale arising at right angles with the first and covered with thin membrane, supplies it with a sail. This unprotected creature serves as food for many predatory tribes, and of these, the most voracious is the barnacle. The flesh devoured, the scales still float for many days, mere wrecks of these gay vessels.