Sailing away in his pearly shell;
He has no need of a compass like us,
Foul or fair weather he manages well!
Over the water he goes—he goes,
Over the water he goes.”
Many more poems of the like nature we might quote, for this little shelled cephalopod has been a favourite with the poets time out of mind, and in some instances they and the less imaginative naturalists have disagreed in their accounts of its form and operations, for instance, Pope says—
“Learn of the little Nautilus to sail,
Spread the thin oar and catch the driving gale.”
“Catch a fiddle-stick,” say some naturalists, the little Nautilus does nothing of the sort; and if you go to him to learn navigation, you will never be much of a sailor; he may teach you how to sink to the bottom and rise again, and that kind of knowledge might be worth something to you if you could breathe under water; and he might teach you how to swim, but not how to sail, for in spite of all poetic theories, he does the former and not the latter. Most usually he walks about at the bottom of the sea on his long arms, something like the Cuttle-fish, feeding on the marine vegetation; the shell is then uppermost; if we could look inside of it we should see numerous little chambers or cells, the larger and outermost of which only are inhabited by the mollusk, the others being filled with air render the whole light and buoyant. Through the centre of these chambers, down to the smallest of them, runs a membranous tube which can be exhausted or filled with fluid at the pleasure of the animal, and the difference thus effected in the weight of the shell enables it to sink or swim; in the latter case, up it goes to the surface, and “keel upwards from the deep,” emerges, as the poet has said, but once there it soon reverses its position. The shell becomes like a boat it is true, but its inhabitant neither points a sail nor plies the oar, but propels itself along stem foremost by a muscular action, which by alternately compressing and loosening a kind of siphon, throws out jets or gushes of water, which by the resistance they meet with from the surrounding fluid, give the desired onward motion, and away the swimmer goes, his long arms gathered closely together, and streaming behind like the tail of a comet, and its round eyes keeping a sharp look-out on either side. Should it espy danger, the body and limbs are withdrawn into the shell, and the fluid driven through the central tube, so as to compress the air in the pearly cells, and down sinks the swimmer once again to his native depths, where
“The floor is of sand like the mountain drift,