I know the difference between a cowry and a cone; but I am not yet acquainted with a multivalve shell—will you show me one?"

"Chiton, or coat of mail, is a good example," said Mr. Elliot; "Pholas is another genus of the same division; it has the appearance of a bivalve. In the Chiton are several lamina, or plates, which are connected by a membrane while the living animal is in the shell; the membrane is pliant, and the inhabitant has the power of contracting itself into a ball, when it would avoid injury, like the insect millepes, that we find under stones in damp places. (Plate 2.) The curious barnacle-shell, Lepas, is another multivalve." (Plate 1.)

"I think we cannot have a more agreeable pursuit for our leisure hours," said Lucy, "than the study of shells. One can bring them out or remove them so easily, that they can cause little inconvenience, which garden-pots often do in town; and then the plants are almost sure to die, whatever care I take of them."

"Collections of shells are frequently to be seen in London," said Mr. Elliot, "which are intended for sale. There are now many places where shells are sold at moderate prices, and young collectors like yourselves can easily avail themselves of the means thus afforded, to obtain even a single specimen. While we remain in town you may visit the British Museum, and become familiar with the rare species of each genus, of which there are many costly specimens. The arrangement adopted for that collection is Lamarck's. You will find the work of this celebrated naturalist on my shelves; it is entitled, 'Histoire Naturelle des Animaux sans Vertèbres.' The three last volumes contain the Conchology."

"It is in French and Latin!" exclaimed Lucy, as she opened a volume.

"Why do you both look so serious?" asked their father. "Are you not students in those useful languages? To what purpose do you learn a language if it be not with a view to reading the works of learned men, whose labours have opened a wide field of knowledge?"

"But so many works on science are written in Latin," said Lucy. "Linnæus, however, has been translated, I know; and as for British botany, we have our own authors in my own dear language."

"The Latin language being universally studied by men of science, it has become the medium of communication between the learned of most countries," observed Mr. Elliot. "I should consider a young person of your age, Lucy, very ignorant who could not read and understand the general style of Lamarck with the occasional aid of the dictionary."

"Do not be discouraged, brother," said Lucy, "my father will assist us: remember how frequently he helps us with our lessons now, provided we do our best. I am resolved to obtain some knowledge of shells this winter."

"A very good resolution," said Mr. Elliot; "and I predict that your usual delight on revisiting our favourite country dwelling will be somewhat increased next spring."

"Because I shall carry down my little collection with the pleasure of knowing more than I did last year."

"Our own coasts, rivers, and ponds afford a variety of shells. The hedge-banks, heaths, and other places, possess their inhabitants."

"Oh," exclaimed Lucy, "I quite forgot the very pretty snails I have so often admired on the heath on a dewy morning: why, we may learn conchology in the open fields as well as botany!"

"Well, then," replied Mr. Elliot, "to-morrow we will apply ourselves to the needful instruction. I must, however, remind you that I do not approve of any animal's life being taken away in order to obtain its habitation. Empty shells are to be found, which will serve perfectly well for specimens; and should the colour not be so bright as you could wish, you will have the delightful consciousness that your amusements have been free from cruelty, and that you have not destroyed the life of any living, harmless creature, in the pursuit of pleasure. Indeed there is as much or more gratification in searching among the rocks, or digging into the sea-sand, with a view to watch the animal in its natural place, as in possessing its empty shell: and who knows what grand discoveries you may both make!

"But I must leave you now—be ready for me after our usual dinner-hour."

CHAPTER II.

"Conchology," said Mr. Elliot, on resuming the conversation with his children, "is that branch of natural history which comprehends the study of testaceous animals, or animals with shell-coverings, and includes those of the seas, the rivers, and the land.

"All shells are formed of carbonate of lime. This you may easily prove by applying a little acid to a shell, and you will find that an effervescence takes place.

"The animals that inhabit shells are bloodless, without bones, but provided with a heart, lungs, and mouth, together with other organs needful to their conformation.

"Testaceous animals have the power of enlarging their habitations; they can also repair any injury that may occur to them.

"Many kinds of shell-fish are made use of by man, and form a valuable article of food, such as oysters, cockles, muscles, scallops. The whelk is also used, and a species of murex.

"A species of cowry is in use for money among some people of Africa; and pearls, so much valued as articles of ornament, are obtained from the oyster and mussel genera.

"Within a few years, conchology has become a study of considerable importance, from its close connexion with geology. Students in the latter science must be well acquainted with fossil-shells, because they form so large a portion of organic remains. Species of recent shells, or those still existing, are also often found in a fossil state, while many fossil genera are now totally unknown in our earth and waters.

"Thus you perceive that while you are obtaining knowledge in one science, you are preparing yourselves for making advances in another, most interesting and wonderful. You, Charles, who are likely to become a traveller, will perhaps in future years find the advantage of my present brief lessons.

"I shall first endeavour to make you acquainted with the system of Linnæus; it is easily learned, and you should be familiar with it, as it is still adopted by some writers on conchology.

"But in order to understand my instructions, you must have a clear idea of the terms that I use in describing a shell; now, therefore, give me your attention while I explain some of those terms to you.