438 TUNICATE MOLLUSCS. 



During this period of existence, our mollusc therefore enjoys to a high degree the 

 characteristic faculties of a living being. It moves, and is brought in relation with the 

 external world by organs of the special senses. Now, however, comes a last metamor- 

 phosis, and this same Teredo loses its organs of motion and sensation, becoming a kind of 

 inert mass in which vegetative life replaces almost entirely the active spontaneity of 

 the animal." 



While we cannot but admire the painstaking research which has brought to light 

 these curious processes in the life of the Teredo, we must dissent from the opinion 

 expressed in the last paragraph. All animals are created to enjoy the life which the 

 divinely implanted instinct forces them to lead, and there is no reason whatever for 

 supposing that the Teredo when sunk in its burrow, without any apparent organs of sight 

 or hearing, is not enjoying its life as thoroughly as when it roamed, the ocean in full 

 possession of both faculties. It seems to me that in speaking of the perfect Teredo as an 

 inert being, more like a vegetable than an animal, M. de Quatrefages loses sight of true 

 philosophy, and falls into the same error as the earlier naturalists, who wrote with 

 scornful compassion of the miserable lives led by the sloth, the mole, and the wood- 

 pecker. They fell into the mistake of judging all other beings by their own standard, and 

 knowing that to be for ever buried underground like the mole, crawling among branches 

 like the sloth, or perpetually hammering at tree-trunks with their mouths like the wood- 

 pecker, would be a most wretched and painful life to themselves, hastily concluded that 

 the creatures above mentioned must be equally miserable under similar circumstances. 



It is, moreover, hardly in accordance with common sense that the animal should be 

 less happy in its perfect than in any preliminary stage of existence, inasmuch as then 

 only can it fully carry out the great law of nature. No one fancies that the butterfly is 

 less happy than the caterpillar, or the bee than the grub, simply because in these particular 

 cases the elements of happiness are more palpable to human senses, or more analogous to 

 our own ideas upon the subject. We have now begun to learn the wondrous powers of 

 adaptation, whereby every living being is rendered happiest in its proper place ; and it 

 surely is but philosophical to infer that whatever might be the case with ourselves, who 

 were not made to burrow in wood, the Teredo, which was created for that express purpose, 

 will enjoy its life like every other being. It is true that man would be very wretched if 

 deprived of eyes and ears, and compelled to spend his existence in a hole just large enough 

 to contain his body ; but he would not be more miserable than the Teredo would be, if 

 removed from its congenial tunnel and forced to live in a warm drawing-room. "What 

 is one man's food is another's poison ;" and the conditions which would inflict unendurable 

 torture upon one being, afford the only means by which another can be made happy. We 

 may as well pity the polar bear for the bitter cold of its native land, or the tropical 

 animals -for the burning heat of their midday sun, as waste our compassion upon the 

 Teredo because it lives in a burrow beneath the waters. 



AN enormous species of this genus, called from its dimensions the GIANT TEEEDO 

 (Teredo gigantea), has been found at Sumatra. This huge mollusc sometimes attains the 

 length of six feet, and a diameter of about three inches, but fortunately for timber, does 

 not make its habitation in that substance, contenting itself with boring into the hardened 

 mud of the sea-bed. The colour of the shelly tube is pure white externally and yellow 

 within. On account of its mud or sand burrowing habits, the specific title of arendria 

 has been applied to this species. 



THE strange-looking objects that are represented in the accompanying illustration have 

 long perplexed systematic naturalists, and even now, although they have been the subject 

 of careful examination by accomplished zoologists, many parts of their economy are 

 enigmatical in the extreme. The order to which they belong is called by the name of 

 Tunicata, because the animals possess no shell, but are covered with an elastic tunic. 

 Some of them are transparent and really beautiful, while others are apparently little more 

 than shapeless masses of gelatinous substance, studded with minute stones, fragments of 

 shells, and coarse sand, overgrown with seaweeds, and perforated by certain bivalve 

 molluscs. 



