2. Larvae mining in leaves, and undergoing their metamorphosis in the leaf. (Hispides and some Halticides.) 3. Short convex larvae, frequently with leathery and pigmented integuments, living exposed on plants. (Most of the Cyclica.) 4. Larvae of short form; covering the body with excrementitious matter. (Some Criocerides.) 5. Peculiar larvae of short form, spiny, and protecting their bodies by excrementitious matter attached by a special apparatus, the excrement itself being modified so as to be suitable for retention. (Cassidides.) 6. Elongate, pallid, larvae with curved abdomen; living in shell-like cases, and undergoing metamorphosis therein. (Most of the Camptosomes, the habits of which are known.) Though our knowledge of these larvae extends to only about 100 out of 18,000 species, the above category by no means includes all the kinds of larvae; Captain Xambeu having recently discovered that the larva of _Chrysochus pretiosus_ lives in the earth feeding on roots after the manner of a _Rhizotrogus_ larva, which it resembles. The larva of _Sagra splendida_ lives {280}inside the stems of _Dioscorea batatas_, in swellings; the group Sagrides, to which it belongs, is a very anomalous one. i. Eupoda. The beetles of the genus _Donacia_ are of special interest. They form, with the genus _Haemonia_, a peculiar group, well represented in Europe, and also in our own country. They are all connected with aquatic plants, the species of _Haemonia_ living entirely under water, while the _Donacia_ live in the imago-state an aërial life, though many of them enter the water with great readiness, and, it is said, are able to take wing from the surface. The larvae live on the roots of aquatic plants, and derive not only nutriment but air therefrom; they pass several months as pupae (or as resting larvae waiting for pupation), under water in cocoons which they construct, and which, incredible as it may seem, are filled with air, not water. Exact details as to the construction of these cocoons are wanting. It was formerly absurdly supposed that the larva swelled itself out to the size of the cocoon it was about to make, and so served as a mould, subsequently contracting. The observations of Schmidt-Schwedt[146] make it, however, more probable that the plant itself furnishes the air which, under pressure of the water (so he supposes), fills the cocoon; the larva wounds the root, piercing to an air-vessel and then constructs the cocoon on this spot, leaving to the last moment an orifice, according to Schmidt, as an exit for the water. The larva uses a similar artifice for obtaining air; it has no gills, but is provided near the extremity of the body with two sharp chitinous processes which it drives into the root of the plant till it penetrates an air-vessel. Schmidt thinks the processes serve as conduits to conduct the air to the tracheae, but Dewitz thinks the air enters the larva