There is little doubt that the idea of the Lernean Hydra, whose heads grew again when cut off by Hercules, originated from a knowledge of the Octopus. Diodorus relates of it that it had a hundred heads; Simonides says fifty; but the generally received statement is that of Apollodorus, Hyginus, &c., that it had only nine. Reduce the number by one, and we have an animal with eight out-growths from its trunk—the type of an Octopus, which is really capable of rapidly developing afresh, and replacing by new ones, one or all of its eight limbs in case of their being amputated or injured.[2] According to the legend, Hercules dipped his arrow-heads in the gall of the hydra, and, from its poisonous nature, all the wounds he inflicted with them on his enemies proved fatal. It is worthy of notice that the ancients attributed to the Octopus the possession of a similarly venomous secretion. Thus Oppian writes:— “The crawling preke a deadly juice contains, Injected poison fires the wounded veins.” Fishermen have been familiar with this animal from time immemorial; but in modern days, although naturalists have occasionally noted some peculiarities of its structure and habits, public attention was never particularly attracted to it until, within the last few years, Victor Hugo brought it again into notice by the publication of his “_Les Travailleurs de la Mer_.” Since then it has been constantly exhibited in aquaria, and “Octopus” has become a household word. THE OCTOPUS. CHAPTER I. THE OCTOPUS AND ITS RELATIVES. It is not my intention to formally portray the anatomy of the Octopus,—the nature and uses of its various organs will be sufficiently indicated in the course of my remarks,—but before giving an account of its life-history and habits, I will briefly describe its affinities, and the position it occupies in the scale of Nature. One of the great primary groups or divisions of the Animal Kingdom is that of the soft-bodied MOLLUSCA; which includes the cuttle, the oyster, the snail, &c. It has been separated into five “classes,” of which the one we have especially to notice is the _Cephalopoda_,[3] or “head-footed,”—the animals belonging to it having their feet, or the organs which correspond with the foot of other molluscs, so attached to the head as to form a circle or coronet round the mouth. Some of these have the foot divided into eight lobes, and are therefore called the _Octopoda_:[4] others have, in addition to the eight feet, lobes, or arms, two longer tentacular appendages, making ten in all, and are consequently called the _Decapoda_.