It seems to me most convenient to use freshly slaked lime, ten to twelve bushels per acre. Since the lime can only kill the slugs when it comes into contact with their skins, it must always be strewn on the land at a time when they are on the crawl, not later than 8 a.m., and only in dry weather. As soon as the slugs are touched by the lime they begin to give out a great deal of slime, and many of them, especially the younger ones, are killed and become black. Very many of the older slugs, however, escape death, since the tenacious slime they give out, when the lime touches them, forms a continuous coat like a cocoon, out of which the slug creeps, now much poorer in water. It is therefore a good plan to strew powdered lime over a slug-infested field twice in succession, leaving an interval of some ten or fifteen minutes. The second strewing brings the lime into contact with those slugs which have just crawled out of their slimy investment in a desiccated condition. They are unable to form a second coating of slime, and if touched for this second time with even the smallest particles of lime they at once contract and die. If a double strewing is repeated very early on the following morning, no slugs will be left alive on the field so treated. CLASS: =LAMELLIBRANCHIATA= (BIVALVE MOLLUSCS). Headless. The mantle consists of two flaps, which secrete two shelly pieces (valves) movably united on the dorsal side (Fig. 43). The foot is usually wedge-shaped. Respiration effected by gills placed in the mantle-cavity, which communicates with the exterior either by the usual respiratory opening, or by a breathing-tube (siphon). Most species are marine, but some live in fresh water. No kind is of agricultural importance. To this class belong the =Oyster= (_Ostrea edulis_), the =Sea Mussel= (_Mytilus edulis_), the tropical =Pearl Mussel= (_Meleagrina margaritifera_), the freshwater =Swan Mussel= (_Anodonta cygnea_), the notorious =Ship Worm= (_Teredo navalis_), etc. =Fifth Sub-Kingdom=: =ECHINODERMATA= (HEDGEHOG-SKINNED ANIMALS). [Illustration: FIG. 145.—The Common Starfish (_Asterias rubens_), seen on the right from above, on the left from below. ]