Though Britain has not suffered from teredo-epidemics in the same measure as Holland, there can be little doubt that the ravages of this mollusc on the timber of our piers and dockyards, cost us a large sum annually. The stoutest oak is riddled through with the same ease displayed in perforating the softer pine; and in some of our seaport towns, especially on the southern coasts, the yearly estimates for repairs of damage done by the ship-worm form no inconsiderable item in the government or local expenditure as the case may be. The most effectual plan for the repression of the teredo and for the prevention of its work of destruction appears to be that of protecting the exposed timber by driving therein short nails with very broad heads. These nails form a kind of armour-casing which is rendered more effective through the chemical action of the water in producing rust. Some molluscs, near neighbours of the teredo, and which burrow for the most part into stone, but occasionally perforate wood, are those belonging to the Piddock-family—the genera _Pholas_ and _Saxicava_ of the naturalist—celebrated by Pliny of old as phosphorescent animals. The _Saxicavæ_ have somewhat elongated shells, by means of which they burrow in rocks and lie ensconced in their dwelling-places, and whose perforated rock-homes are eagerly sought after by all who delight in forming rockeries in their gardens. These molluscs have ere now caused fears for the safety of Plymouth breakwater, through the persistence with which they excavated their burrows into the substance of the stones. And as has been well pointed out, the destructive action of these molluscs may pave the way for an inroad of the sea; a riddled mass of rock or stone being rendered through their attack liable to disintegration from the action of the waves. A final example of an animal enemy of man which as regards size is to be deemed insignificant when compared with the teredo, but which nevertheless adds by its destructive work to our annual expenditure, is the little crustacean known as the _Limnoria terebrans_, or popularly as the wood-boring shrimp or ‘gribble.’ This animal belongs to the group including the familiar ‘Slaters’ or ‘Wood-lice,’ found under stones and in damp situations, and by means of its powerful jaws burrows deeply into wood of all kinds. Occasionally, the ship-worm and gribble have been found at work in the same locality and have committed ravages of great extent; the latter, on account of its small size, being more difficult of detection and eradication than its molluscan neighbour.