One more section remains to be noticed. The jelly-fishes which belong to it have a rudimentary skeletona 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 alonethey 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.
We find in another species a still more perfect rigging. In it (Rataria ) the crest is supplied with muscular bands, by means of which the sail can be lowered or raised at pleasure. These adaptations of structure are full of interest. Nothing can be more admirable than the sailing-gear of these little creatures. They have to traverse the surface of the ocean amidst all diversities of weather. Paddles alone would not suffice for them. They must be enabled to take advantage of the winds. Sails, therefore, are added, and the mightiest agents in nature are commissioned to speed the little voyagers on their way.
We have already mentioned that some of the jelly-fishes possess the power of stinging. Only a few of the larger species, however, seem to be thus endowed; and the name sea-nettle is by no means applicable to the class as a whole. The poisonous fluid which produces the irritating effect on the skin, and no doubt paralyses the creatures upon which the jelly-fish feeds, is secreted by the arms. By means of its poison-bearing tentacles, the soft, gelatinous medusa is more than a match for the armed crustacean and the scale-clad fish. We take from Professor Forbes the following graphic description of one of the stinging species:'The Cyanæa capillata of our seas is a most formidable creature, and the terror of tender-skinned bathers. With its broad, tawny, festooned, and scalloped disk, often a full foot or more across, it flaps its way through the yielding waters, and drags after it a long train of ribbon-like arms, and seemingly interminable tails, marking its course when its body is far away from us. Once tangled in its trailing "hair," the unfortunate who has recklessly ventured across the graceful monster's path too soon writhes in prickly torture. Every struggle but binds the poisonous threads more firmly round his body, and then there is no escape; for when the winder of the fatal net finds his course impeded by the terrified human wrestling in its coils, he, seeking no contest with the mightier biped, casts loose his envenomed arms, and swims away. The amputated weapons severed from their parent body vent vengeance on the cause of their destruction, and sting as fiercely as if their original proprietor itself gave the word of attack.'
We now approach the most extraordinary portion of the history of these creatures. Recent investigations have brought to light the most interesting facts respecting their reproduction and development. It is now known that the young jelly-fish passes through a series of transformations before reaching its perfect state.
At certain seasons, eggs are produced within the body of the parent in appropriate ovaries, where they are retained for a time. They are then transferred to a kind of marsupial pouch, analogous to that of the kangaroo, where their development proceeds. After passing through certain changes here, the egg issues from the maternal pouch as an oval body, clothed with ciliaan animalcule in external aspect, and as unlike its parent as can well be imagined. For awhile the little creature dances freely through the water, and leads a gay, roving life; but at last it prepares to 'settle;' selects a fitting locality; applies one extremity of its body to the surface of stone or weed, and becomes attached. And now another change passes over it. The cilia, no longer needed, disappear. A mouth is developed at the upper extremity of the body, furnished with a number of arms. Gradually this number increases, and the jelly-fish now appears in the disguise of a polype, which feeds voraciously on the members of the class from which it has itself so lately emerged. At this point there is a halt. The medusa remains in its polype state for some months. At the expiration of this term, a strange alteration in its appearance begins to take place. Rings are formed round its body, from ten to fifteen in number. These gradually deepen, until at length it is literally cut up into a number of segments, which rest one upon the othertheir upper margins becoming elevated, and divided into eight lobes. It is, in fact, a pile of cup-shaped pieces, very loosely connected together. A little later, these pieces free themselves successively, and the sedate polype disappears in a company of sprightly young medusæ. These beings, indeed, still differ in some respects from the adult animal; but the differences gradually vanish, and we have