This beautiful molluscous animal inhabits the tropical seas, and is also seen in high latitudes during the summer months[4] of the year. When first removed from the water, it excites the admiration of the spectators by the elegant and vivid colours with which it is adorned. These tints, however, are as evanescent as they are brilliant; and soon after this animal is taken from its native element, the crest sinks; the bright crimson, green, and purple tints lose their brilliancy, and the beauty which had previously excited so much admiration fades, and at last totally vanishes. There are a number of species of the genus;[5] but the one most commonly seen is the _Physalia pelagica_ of Lamarck, (_Holothuria physalis_ of Linn.) They are known to our seamen as the “Portuguese men of war,” and galére or frégate among the French, from having some resemblance to a small vessel resting tranquilly on the surface of the water during a calm, at which time they are more readily discerned than during strong breezes: they have also been confounded by many persons unacquainted with natural history with the _Nautilus_. The figure of this species is somewhat ovate; the upper portion resembles an inflated bladder, rounded at one extremity, and with a beak-like termination at the other. On the summit or back is a crest or ridge, slightly elevated, sulcated, and fringed at the edges: the whole of this part of the animal is of a light blue, with occasional streaks of delicate sea-green, and tinged with brilliant crimson: this portion of the animal is filled with air, and, although I have heard it frequently asserted that the animal has the voluntary power of collapsing the bladder on the approach of tempestuous, or inflating it on a return of fine weather, yet I do not credit the remark, considering it is more probably a seaman’s tale than the result of a naturalist’s observation. On examination, no apparatus is found by which such an effect could be produced; and if it actually possesses such a power, why is it not exercised in every moment of peril?—for, when we approach the animal to capture it, or when it is taken from the water, no such change occurs; the bladder still remains inflated, and can be preserved thus distended either in a dried state or by placing it in alcohol. During strong breezes, I have seen them floating on the waves; but, from the ship passing at that time rapidly through the water, they are then more rarely observed. I have also seen them thrown in tempestuous weather on the beach at New South Wales, the bladder portion of the animal still remaining inflated. From these, and other reasons which might be adduced, the assertion cannot be considered as the result of actual observation. Situated at the under portion of the animal is a mass of tentaculæ, some short and thick, others long, filiform, and extending to several yards in length: these seem to consist of a chain of globules, filled with an