320 NATURAL HISTORY. 



the blade, and not the outer lobe, which is subject to disappear ; and in the tarsi it is the first joint, 

 and not the fourth, which is reduced in size. In their general form and habits also the two families 

 are very different. The Trogositidse are of much larger average size, longer and narrower in form 

 (except in a few aberrant genera), and often of rich metallic colours. They are essentially wood- 

 feeders, and are never found on flowers or in animal substances. Some few species, e.g., Trogosita 

 mauritanica, have acquired a preference for wheaten flour and other kinds of cereal meal, and multiply 

 at times in meal-bins, so as to prove a great pest to the miller and the baker. The family is generally 

 distributed over the earth. About one hundred and fifty species have been described. 



The COLYDIID.E are a group of very small Beetles, living under bark or in rotten wood or fungi, of 

 oblong and flattened or long and slender form, distinguished from the preceding family, inter alia, by 

 their four-jointed tarsi. The abdomen, which in the preceding families of Necrophaga has all its 

 segments free, here shows a more consolidated structure, only the last, or the last two segments being 

 separately movable, a character which indicates a tendency towards a higher type than either of the 

 two tribes Necrophaga and Brachelytra. The maxillae have two lobes, and the antennae are more or 

 less clubbed at the extremity. 



The RHYSODID^E are small wood-eating Beetles, of similar form to the more elongated genera of 

 the preceding family. They are distinguished at first sight by the deep furrows which score the upper 

 surface of their body in a longitudinal direction. Their antennae are not clavate, but formed of 

 rounded joints of nearly equal width, and eleven in number. About a dozen species only are known. 



The CUCUJID^: are also wood-eaters, but more exclusively restricted to the bark of ti-ees than the 

 members of the preceding families. Their general form is oblong, and their colours pale or brown. 

 Nearly all the numerous species are, in correspondence with this confined habitat, more or less 

 flattened, some of them so much so that their bodies are scarcely thicker vertically than a sheet of 

 ordinary writing-paper. The antennae are long, often slender, eleven-jointed, with joints more or less 

 rounded in form, the three last thickened into a club. The abdomen has six nearly equal segments, 

 all free. The tarsi are normally five-jointed, but the hind pair in the males of many species have only 

 four joints, and in many others the first or the fourth joint is much reduced in size. The mandibles 

 are always well developed, and in some species are large and exserted. There are few exceptions in 

 this family to the prevailing sub-cortical mode of life. One of these is furnished by the genus 

 Silvanus, which infests sugar-casks and meal-bins. The species are sometimes found alive on the 

 windows of our houses, or floating dead in our teacups. The flattened species are excessively 

 numerous and varied in tropical America, living gregariously under the bark of recently-felled trees, 

 so closely fitting that the blade of a penknife is with difficulty forced underneath. 



The CRYPTOPHAGID.E differ in general appearance from Cucujidae by their more oblong or 

 elliptical form and pubescent surface. Nearly all are Beetles of very small size, inhabiting decayed 

 wood, vegetable detritus, boleti, Ants' nests, and so forth. The antennae are eleven-jointed, and have 

 a distinct three-jointed club ; the elytra are entire, covering the whole abdomen, which has five free 

 joints ; and the tarsi, with some exceptions in the males, are five-jointed. Most of the 300 species 

 hitherto described are European, but many are found in Siberia and North America, and a few are 

 known from warmer climates. The species of one genus (Telmatophilus) are found on aquatic plants ; 

 others of very diminutive size, belonging to the genus Ephistemus, attack mouldy paper, and are some- 

 times seen in old books in neglected libraries. 



The LATHRIDIID^E consist, like the preceding, of very small oblong or linear Beetles, of pale 

 brownish colours, having antennae of eleven joints, with a club formed sometimes only of one, at other 

 times of two, and again of the ordinary number of three joints. The tarsi consist only of three simple 

 joints. Their habits are very similar to those of the Cryptophagidae. More than 350 species are 

 known, of which a large number inhabit the British Islands. 



The MYCETOPHAGID^E differ from the six preceding families in their oblong or oblong-ovate, 

 convex form of body, fine pubescent clothing, and the ornamentation of their wing-covers with reddish 

 belts or spots. Their antennae are clubbed, and their abdomen consists of five movable, nearly equal 

 segments. The tarsi have only four distinct joints, reduced to three in the anterior feet of the males. 

 They live in boleti and fungi, or under the bark of dead trees. 



The THORICTID^E are a small group of minute, broad, and convex Beetles, remarkable for the great 



