The common stag-beetle, _Lucanus cervus_, is our largest British beetle. The larva much resembles that of _Melolontha vulgaris_, but attains a larger size, and the anal aperture is placed longitudinally instead of transversely; it lives in decaying wood, or eats the roots of trees without being injurious; its life in this state lasts about four years; the pupal period is passed through rapidly, and the perfect Insect may remain for months underground before it becomes active; this occurs in June and July. This larva stridulates by scraping certain hard tubercular ridges on the third pair of legs, over a specially adapted rough area at the base of the second pair. The Passalidae and Lucanidae are united by some authorities as a group called Pectinicornia; the term Lamellicornia being then confined to the Scarabaeidae. The Passalidae appear, however, to be really more nearly allied to the Scarabaeidae than to the Lucanidae. FAM. 3. SCARABAEIDAE (_Chafers_).—_The leaflets of the antennae are well coadapted, and are susceptible of separation. The elytra {195}usually leave the pygidium uncovered. The number of visible ventral segments is usually six, or at the sides seven, not five, as in Lucanidae and Passalidae._ This is one of the most important families of Insects. About 13,000 species are already known; as some of them are highly remarkable creatures on account of the males being armed with horns, they are figured in many works on natural history. There is great variety of form, and the following five sub-families may be adopted, though authorities are by no means agreed as to the classification of this extensive family, which, moreover, be it remarked, is increasing by the discovery of about 300 new species every year. Abdominal spiracles placed in a line on the connecting membranes, and entirely covered by the wing-cases (Laparosticti). Sub-fam. 1. COPRIDES.[81] Abdominal spiracles placed almost in a line, but only the basal three on the connecting membranes; the terminal one usually not covered by the wing-cases. Sub-fam. 2. MELOLONTHIDES. Abdominal spiracles placed in two lines, the basal three on the connecting membranes, the others on the ventral segments (Pleurosticti). The claws of the tarsi unequal. Sub-fam. 3. RUTELIDES. The claws of the tarsi equal; the front coxae transverse, but little prominent in the descending axis. Sub-fam. 4. DYNASTIDES. The claws of the tarsi equal; the front coxae more prominent, shorter transversely. Sub-fam. 5. CETONIIDES.