another member of that queer ology family, deriving its name from two Greek words signifying soft, and a discourse; hence it means a discourse upon soft, or soft-bodied, animals, that is _mollusca_. It is only a part then of _Malacology_ that we have to do with; that part which relates to the shell-inhabiting mollusks, and strange creatures enough some of these are. We will have a look at them presently; just now it will be sufficient to observe that the _mollusca testacea_, or soft-bodied animals, furnished with shells, possess the power of exuding, that is, discharging from various parts of their bodies a sticky kind of fluid, which mixing with the chalky matter collected from the water, and becoming hard, forms, in process of time, the shelly covering which is at once a dwelling and a defence for the inhabitant. Miss Pratt, in her delightful book on “Common Things of the Sea Coast,” observes of these shells that, “We gather up those which we find, and looking at their structure would fain know something of the inmate of such a dwelling. All nature proclaims the goodness of God. We hear that the bird which wings its way over our heads has a song of joy; the bee hums delightedly by us; and the little shrimp which darts in the clear pool, seems full of merriment. Was the inmate of the shell less cared for by its Maker? No doubt the little builder had some sense of joy, as he framed from his own substance the house which excites our admiration. Doubtless his existence, short and sluggish as it was, had its own consciousness of pleasure; and obscure as is his history, and little calculated as such a creature might seem to perform an important part in the economy of creation, yet we know that he had a work to do, not only for the living creatures of the sea, but for the well-being of man himself.” CLASSIFICATION OF SHELLS. The great naturalist Linnæus divided shells into thirty-six genera, each of which comprised a number of species; of these species somewhere about two thousand five hundred have been described and classified; the varieties, more or less distinct, are almost countless. Of shells found on and about the British Isles, there are about five hundred and fifty species, or, we should rather say were, for diligent enquirers into this branch of Natural History, are almost daily adding to the number. We have already seen that shells are sometimes called _Crystalline_, and sometimes _Granular_, in accordance with certain peculiarities of construction before mentioned: this is one mode of division; there are several others made use of in different systems of arrangement, which only a deeper study of the subject than can be here entered upon, would enable one to understand; the plainest and most common, however, is that which has reference to the form of the shell, which is one of these— [Illustration: UNIVALVE. BIVALVE. MULTIVALVE. Whelk. Mussel. Barnacle.]