The animal enemies of man, concerning which we purpose to say a few words in the present paper, belong to a different sphere from that at which we have just glanced. Some of the most powerful marauders upon human territory belong to the Mollusca or group of the true shell-fish, and present themselves as near relations of the oysters, mussels, and their allies. The molluscs which become of interest to man in other than a gastronomic sense, possess, like the famous oyster, a bivalve shell, or one consisting of two halves. In the first of man’s molluscan enemies to which we may direct attention, the shell is of small size, and so far from inclosing the body of the animal, appears to exist merely as an appendage to one extremity, which for want of a better term, we may name the head—although, as every one knows, no distinct head exists in the oyster and its kind. Suppose that from this head-extremity, bearing its two small shells, a long worm-like or tubular body is continued, and we may then form a rough and ready, but correct idea of the appearance of the famous ‘ship-worm’—the _Teredo_ of the naturalist. This animal was first styled the ‘ship-worm’ by Linnæus and his contemporaries; and in truth it resembles a worm much more closely than its shell-fish neighbours. As a worm, indeed, it was at first classified by naturalists. But appearances in zoological science are as deceptive as they are known proverbially to be in common life, and the progress of research afterwards duly discovered beneath the worm-like guise of the teredo, all the characters of a true mollusc. The long body of the mollusc simply consists of the breathing-tubes, by which water is admitted to the gills, being extremely developed, the body proper being represented by the small portion to which the two small shells are attached. The importance of the ship-worm arises from the use it makes of these apparently insignificant shells as a boring-apparatus; and any sea-side visitor, residing on a coast where an ocean-swell or severe storms strew the shore with drift-wood, has but to use his eyes to assure himself of the extent and perfection of the ship-worm’s labours. Pieces of drift-wood may be seen to be literally riddled by these molluscs, which live in the burrows they thus excavate. Each habitation is further seen to be coated with a limy layer formed by the tubular body, and the boring for the most part is noted to proceed in the direction of the grain of the wood. The little excavator turns aside in its course, however, when it meets with a knot in the wood, and an iron nail appears of all things to be the ship-worm’s greatest obstacle—a fact which has been taken advantage of, as we shall presently see, by way of arresting its work of destruction.