FAM. 43. DERMESTIDAE.—_Tarsi five-jointed; antennae usually short, with the club frequently very large in proportion, and with the under side of the thorax bearing a hollow for its reception. Front coxae rather long, oblique: hind coxa formed to receive the femur when in repose._ A family of 300 or 400 species of small or moderate-sized beetles; the surface, usually covered with fine hair, forming a pattern, or with scales. _Byturus_, the position of which has long been disputed, has now been placed in this family; it has a more imperfectly formed prosternum, and the third and fourth joints of the tarsi are prolonged as membranous lobes beneath; the hind coxae leave the femora quite free. Dermestidae in the larval state nearly all live on dried animal matter, and are sometimes very destructive; some of them totally destroy zoological collections. They are very remarkable on account of the complex clothing of hairs they bear; they have good powers of locomotion, and many of them have a peculiar gait, running for a short distance, then stopping and vibrating some of their hairs with extreme rapidity. They exhibit great variety of form. Many of them are capable of supporting life for long periods on little or no food, and in such cases moult an increased number of times: pupation takes place in the larval skin. _Anthrenus fasciatus_ has been reared in large numbers on a diet of dried horse-hair in furniture. The young larva of this species observed by the writer did not possess the remarkable, complex arrangement of hairs that appeared when it was further grown. The most curious of Dermestid larvae is that of _Tiresias serra_, which lives amongst cobwebs in {242}old wood, and probably feeds on the remains of Insects therein, perhaps not disdaining the cobwebs themselves. Attention has been frequently called to the hairs of the larvae of these Insects, but they have never been adequately discussed, and their function is quite unknown. FAM. 44. BYRRHIDAE (_Pill-beetles_).—_Oval or round, convex beetles; tarsi five-jointed, front coxae not exserted, transverse; hind coxa shielding the retracted femur. The whole of the appendages capable of a complete apposition to the body._ Although a small family of only 200 or 300 species, Byrrhidae are so heterogeneous that no characteristic definition that will apply to all the sub-families can be framed. Very little is known as to their life-histories. _Byrrhus pilula_ is one of our commonest beetles, and may be found crawling on paths in early spring even in towns; it moves very slowly, and when disturbed, at once contracts the limbs so completely that it looks like an inanimate object. The larva is cylindrical, soft; the prothoracic and last two abdominal segments are larger than the others, the last bearing two pseudopods; its habits are unknown, and no good figure exists of it.