In this creature, as in many of the lower animals, there is a remarkable power of retaining vitality after the most serious injuries; nay, in portions actually severed from the body, it will continue for some time. Mr Patterson, in his excellent _Introduction to Zoology_, mentions that on one occasion he divided a fragment of the body of a beroe, lately taken from the shore and shattered by a storm, 'into portions so minute that one piece of skin had but two cilia attached to it, yet the vibration of these organs continued for nearly a couple of days afterwards!' But we must leave the beroe, charmer though it be. Another member of this section--the _Ciliograde acalephae_, as they are called--is the Girdle of Venus, which resembles a ribbon in form, and is sometimes five or six feet in length, covered with cilia, and brilliantly phosphorescent. This must be one of the most beautiful of the _fireworks_ of the ocean. The jelly-fishes of another section are furnished with one or more air-bags, which assist them in swimming, and hence bear the name of _hydrostatic acalephae_. In the Portuguese man-of-war (_Physalia_), the bag is large, and floats conspicuously on the surface of the water. From the top of it rises a purple crest, which acts as a sail, and by its aid the little voyager scuds gaily before the wind. But should danger threaten--should some hungry, piratical monster in quest of a dinner heave in sight, or the blast grow furious--the float is at once compressed, through two minute orifices at the extremities a portion of the air escapes, and down goes the little craft to the tranquil depths, leaving the storm or the pirate behind. In one species (_Cuvieria_), the floats are numerous and prettily ranged round the margin of the body. Resting on these, the creature casts about its long fishing-lines, and arrests the passing prey. One more section remains to be noticed. The jelly-fishes which belong to it have a rudimentary skeleton--a plate which supports the soft, circular body. From the lower part of the body hang numerous tentacles (_cirri_), amidst which the mouth is placed. Probably these multitudinous arms assist in locomotion; and, hence the name of the family, _Cirrigrades_. Amongst the creatures of this division we meet with some very interesting locomotive apparatus. There are some of them by no means obliged to trust to their oars alone--they have also sails. The _Velella_, large fleets of which visit our seas at times, has a plate (the mast) rising from its bluish disk or deck, covered with a delicate membrane (the sail) of snowy whiteness, by means of which it traverses the ocean. This sail, it has been noticed, 'is set at the same angle as the lateen-sail' of the Malays. We cannot doubt that it is admirably suited to its purpose, and the Malays may be proud of having nature as a voucher for their contrivance.