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308 appendage at their base. The lower edge of each of these plates is finely toothed throughout its whole extent, the teeth directed backwards, and at the same time turned a little outwards. The surface of these plates is very smooth internally, but the outer side is partly covered with very closely placed oblique striæ and elevated lines. When the instrument is put in motion on the surface of a leaf, or on a twig, the small teeth act as a saw, while the lateral ridges perform the office of a file or rasp. By this means a suitable opening is soon formed for receiving the eggs. These are sometimes placed within the woody substance of the branches of shrubs, but more commonly they are attached to the leaves. An instance of the former sort is observed in the Rose Saw-fly, (Hylotoma Rosæ,) and a familiar example of the latter in the species which infests gooseberry and currant bushes, which arranges its eggs in rows along the mid rib and principal nervures of the leaves. In all cases the eggs are not long in being hatched; and the young larvæ generally find their appropriate food in the leaves of the plant on which the provident mother had placed them. From the general resemblance these larvæ bear to the caterpillars of butterflies and moths, they are called false caterpillars, as the word caterpillar ought to be restricted to the former. A very slight examination is sufficient to enable one to discover decided marks of distinction between them. The true caterpillars—the larvæ of Lepidoptera—have never