bristle-tail of the genus Campodea, is often called a _campodeiform_ larva (Brauer, 1869). From such as these, a series of forms can be traced among larvae of beetles, showing an increasing divergence from the imago. The well-known wireworms--grubs of the Click-beetles (Elateridae)--that eat the roots of farm crops, have well-armoured bodies, but their shape is elongate, cylindrical, worm-like; and their legs are relatively short, the build of the insect being adapted for rapid motion through the soil. The grubs of the Chafers (Scarabaeidae) are also root-eaters, but they are less active in their habits than the wireworms, and the cuticle of their somewhat stout bodies is, for the most part, pale and flexible; only the head and legs are hard and horny. Usually an evident correspondence can be traced between the outward form of any larva and its mode of life. For example, in the family of the Leaf-beetles (Chrysomelidae) some larvae feed openly on the foliage of trees or herbs, while others burrow into the plant tissues. The exposed larvae of the Willow-beetles (Phyllodecta, fig. 14) have their somewhat abbreviated body segments protected by numerous spine-bearing, firm tubercles. But the grub of the 'Turnip Fly' (Phyllotreta) which feeds between the upper and lower skins of a leaf, or of _Psylliodes chrysocephala_ (fig. 15), which burrows in stalks, has a pale, soft cuticle like that of a caterpillar. [Illustration: Fig. 14. (_a_) Willow-beetle (_Phyllodecta vulgatissima_) and its larva (_b_). Magnified 5 times. After Carpenter, _Econ. Proc. R. Dublin Soc_. vol. I.] [Illustration: Fig. 15. (_a_) Cabbage-beetle (_Psylliodes chrysocephala_) magnified 5 times, and its larva (_b_) magnified 12 times.] In the larvae of the little timber-beetles and their allies (Ptinidae), including the 'death-watches' whose tapping in old furniture is often heard, a marked shortening of the legs and reduction in the size of the head accompany the whitening and softening of the cuticle. This shortening of the legs is still more marked in the larvae of the Longhorn Beetles (Cerambycidae) burrowing in the wood of trees or felled trunks; here the legs are reduced to small vestiges. [Illustration: Fig. 16. _a_, Grain Weevil (_Calandra granaria_); _b_, larva; _c_, pupa. Magnified 7 times. After Chittenden, _Yearbook U.S. Dept. Agric._ 1894.] Finally in the large family of the Weevils (Curculionidae, fig. 16) and the Bark-beetles (Scolytidae), the grubs, eating underground root or stem structures, mining in leaves or seeds, or tunnelling beneath the bark of trees, have no legs at all, the place of these limbs being indicated only by tiny tubercles on the thoracic segments. Such larvae as these latter are examples of the type called _eruciform_ by A.S. Packard (1898) who as well as other writers has laid stress on the series of transitional steps from the campodeiform to the eruciform type afforded by the larvae of the Coleoptera.