To revert to other classes that occur to me as suitable objects for an Aquarium, I may mention the “Red-noses,” as they are graphically termed (_Saxicava rugosa_), a colony of which, peeping out of their holes in the rock, would form a very striking object; and if a piece of their native rock could be detached sufficiently deep not to disturb them in the recesses of their tube-like burrows, their removal “_en bloque_” would not be difficult. When touched, the Red-nose squirts a stream of water at you in defiance, and darts back into his cavern. He is a small bivalve, having his inner or immediate home within two rough brown shells. The double-tubed proboscis with which he is furnished is extended, when in search of food, to the mouth of his cave, in which position the appearance of its ruddy terminus has given to this tribe the characteristic name of “Red-noses.” How he contrives to bore a hole in the solid rock, with any of the soft pulpy members with which he is furnished, appears a mystery. Other Conchifers have, however, similar capabilities, their ingenuity not being confined to rocks, and their industry not being always harmless. Such, for instance, is that of the Teredo, or Ship-worm, a species of which has long proved so inimical to the formation of a Russian fleet in the Black Sea—the late war having, however, proved a far more serious impediment to the development of that portion of the Russian navy. The Sea-Leaf, formed of twenty thousand or more cradles for young Polypes, is also a curious object. It is the Polyzoön, sometimes called the Hornwrack. A few of the translucent Medusæ, in a young stage of their existence, might be procured and tried, though their transport would be difficult; and a group of creatures, of the genus _Zoöthamnium_, forming, as they do, an object like a little tree of glass, covered with trumpet-shaped bells, of the same crystalline aspect, each exhibiting its rotating circle of minute cilia in rapid motion within, would form a singular and beautiful complement to the wonders of the Aquarium, if its removal from its native depths, and its location in its new home, could be successfully managed. [Illustration] ------------------------------------------------------------------------ CHAPTER IX. CONCLUSION. In conclusion, a few general remarks may be made, the observance of which will usually ensure success in the formation of an Aquarium. In the first place, if the vessel in which the Aquarium is to be established be home-made, care must be taken not to use any cement that has a disagreeable smell—which would be very soon fatal to creatures accustomed to the pure waters of the ocean. Scott’s cement is said to be better than putty, for fixing in the glass to the columns at the angles.