Rarely, if ever, have I passed by this storehouse of great marvels without regretting it, for indeed it has no equal in the world. Tanks of fish are kept in many cities; the only aquarium is at Naples. There alone can one stand and watch the actual stress and movement of the life which passes in the sea, that animal life of myriad shapes and colours which is so like the plants and which while rooted to a rock, and spreading long translucent tendrils like a frond of seaweed, will yet curl and uncurl, swaying this way and that in search of food, or in the effort to escape some enemy it fears. For the depths of the sea are full of enemies, and every sense of those which dwell beneath it is alert. There one may see the tube-dwelling worms, thrust out from the mouth of their tall cylinders like a feathery tuft of tendrils, a revolving fan, which spins and spins until some sea-horse floating up erect and graceful comes too close, and instantly the fan closes, the tendrils disappear and lie hidden till the danger has gone by. Far along the rock clefts, high and low throughout the pools, there is a perpetual watchfulness and motion, a constant stir and trembling; and the provision which the lowest animal possesses for the protection of its life is in quick and momentary use, laying open such a revelation of the infinite resources of nature as itself makes this cool chamber one of the most interesting places in the world. But if a man go there for beauty only, in what profusion he will find it! The green depths of the tanks are all aglow with soft rich colour. The sea beneath the cliffs at Vico is not more blue on the softest day in spring than the fish which glide by among these shadows; nor are the lights seen from Castellammare when the sun drops down behind Ischia and the rosy flushes spread along the coast, more exquisite than the soft pink scales which glance through the arches of the rocks. Turquoise and pearl, emerald and jacinth, the gleams caught from the hidden sun above reflect the hues of every gem. The strange, dense vegetation, the quick flash of moving gold and purple, reveal a world of marvellous rich beauty; and if it be indeed the case that those bold divers of past days who dared to plunge out of the bright sun into the dusk and dimness of the ocean depths saw there the orange sponges, the waving forests of crimson weed, and all the myriad colours of the moving fishes glinting through them, it is no wonder that they came back into the world of men spreading tales of countless jewels, and unnumbered treasures, which lie buried in the caves and grottoes of the sea.