566 



THE RH1Z08TOMA. 



Lest any of my readers should become fellow-sufferers with myself, I advise them to be 

 very careful when bathing after a strong south-west wind has prevailed, and if ever they see a 



tawny mass of membranes 

 and fibres floating along, to 

 retreat at once, and wait 

 until it is at least a hundred 

 yards away. Some may 

 suppose that this advice is 

 needlessly timid, but those 

 who have once felt a single 

 poison thread across their 

 hand or foot, w r ill recognize 

 that discretion is by far the 

 wisest part to be played 

 whenever there is the least 

 danger of being stung by 

 the Cyanjea. 



THE last family, of 

 which a small specimen is 

 represented in the accom- 

 panying illustration, is 

 easily known by the 

 absence of a mouth. In 

 the typical genus, RHIZOS- 

 TOMA, the footstalk is 

 deeply scooped into semi- 

 lunar orifices, and the eight 

 cartilaginous arms are 

 without fringes. 



RHIZOSTOMA. lihizostoma cvvieri. 



BEFORE taking a final leave of these remarkable beings, it is needful that we should 

 briefly notice the strange metamorphosis through which some of them pass before they assume 

 their well-known form. Experiments were made on a species of Chrysaora, by Sir John 

 Dalyell, with the following result : When first sent into the world, the young Medusae were 

 little flat, worm-like creatures, too minute to be examined by any except the highest powers 

 of the microscope. By degrees, these tiny beings settle doAvn to one spot and affix themselves, 

 the body lengthens, arms begin to be shown, and after a while the strange creature is developed 

 into the being known as the Hydra tuba. 



Satisfied, apparently, with its condition, the Hydra remains in the same spot for some 

 time, and produces a number of young Hydras, which sprout like buds from its sides, and, 

 when separated, resemble their parent. Here, we might naturally imagine to be the end of its 

 history, for, with almost all animals, when a being is able to produce young, it is considered 

 as having attained the utmost development of which it is capable. The Hydra, however, has 

 yet other phases through which to pass. Towards spring, its body becomes much lengthened 

 and wrinkled, so as to form a number of folds, just as if a series of threads had been tied 

 tightly round it, one below the other. The upper rings now rapidly expand and the folds 

 deepen, until the animal resembles a number of saucers regularly increasing in size, laid 

 upon each other. The edges of each saucer are developed into two-cleft rays, and in this 

 condition the animal proves to be the beautiful zoophyte discovered by M. Sars, and called 

 the Strobila. 



These are, indeed, strange vicissitudes in life, changes more marvellous than even those 

 wrought by water and magic words, in the old days when Haroun Alraschid ruled the faithful. 

 There is yet more to come. The uppermost and largest disc or saucer now lengthens its rays 



