Edward and Lewis were much delighted with the account their mother gave them of the barnacle, and of the surprising reappearance of the sunken vessel. “Mamma,” said Lewis, “I believe I shall always know the _lepas_, the _lepas anatifera_ I mean, when I see it again. Do you think you could get for us any specimens of the other orders belonging to this class?” Mrs. Ashton promised to do so if possible. “Lewis,” she said, “I think you will not call conchology so very dry a subject another time, if I may judge from the interest you have taken in it: but perhaps you have learned enough of classification for to-day.” The children begged to be allowed to look at the shells a little longer; and again and again admired their bright colours and elegant forms. “The most beautiful shells,” said Mrs. Ashton, “are brought from the Red Sea and the East Indies. Those which are found in the West Indies are less brilliant; and the shells of colder regions possess still less lustre and variety of colours: so that this difference may very reasonably be attributed, in some measure, to solar heat: perhaps, too, those seas in which the most brilliant shells are found, may furnish a greater supply of nourishment to the animals which inhabit them, and thus cause their shelly coverings to increase in size and beauty.” “Do you really mean, mamma,” said Edward, “that shells grow?” “Yes, my dear: naturalists tell us, that an infant shell-fish is covered with a testaceous coating, which is gradually increased by the supply of a viscous substance, exuding from the animal, until it is furnished with a dwelling completely adapted to its wants and situation. It is very interesting to notice the great variety of habitations provided for the different species, and to see how admirably each one is in accordance with the instincts of the occupant. Some are sheltered by thick coverings, which protect them from the beating of the boisterous waves; others, which inhabit the still waters of ponds or ditches, have light and fragile dwellings. The shells of some animals are in form like little vessels, the valves of which they open to the breeze, and thus float on the surface of the waves; others, inclosed in cases, which remind us of the diving-bell, lie hid in ocean’s caves; or occasionally descend to the very bottom of the sea. The limpet, in his conical dwelling, lives like a solitary hermit on the sea-coast: the _pinna_ has a shell so large as to admit other guests: the _chiton_ rolls himself up in the plaited folds of his armour, at the first approach of danger; while other fish, apparently more defenceless, have shells of such a form as to enable them to make a speedy retreat from their enemies.”[1] Lewis wanted much to know what the armour of the _chiton_ was; but just as he was going to make the inquiry, the sound of a horn attracted the attention of the little party. “Can it be six o’clock already?” cried he.