728 CLASS IV. INSECTA. 



well developed terga, and somewhat resemble wood-lice. Those of Silpha 

 run about in search of carrion. 



Fam. 16. Scydmaenidae. Minute. Five-segmented tarsi. Six 

 visible abdominal segments. Elytra cover, or almost cover, abdomen. A 

 cosmopolitan family of very small black or brown beetles living amongst 

 moss, under bark or stones, and in ants' nests. They feed on mites. 



Fam. 17. Gnostidae. Minute. Five-segmented tarsi, three seg- 

 mented antennae. Elytra conceal abdomen which has apparently but 

 three segments ; the apparent first however consists of three fused plates. 

 Two species found in ants' nests in South America constitute this family. 



Fam. 18. Pselaphidae. Minute. Elytra shortened so as to cover at 

 most half the abdomen. Maxillary palps large. Abdominal segments 

 rigid. Tarsi three-segmented. A large family of peculiar beetles ; most 

 found only in ants' nests-. They produce from pubescent tufts some 

 secretion which the ants eat, and in return, at least in some cases, the ants 

 feed them. Claviger has been seen to eat the ant larvae. 



Fam. 19. Staphylinidae. Elytra shortened so as usually to cover but 

 two of the abdominal segments. Ten abdominal terga visible, and these 

 are hardened, and the segments very mobile. Three to five tarsal segments. 

 An enormous cosmopolitan family with some nine thousand species known 

 as Rove-beetles or " Devil's coach-horses." The metathoracic wings, like 

 those of the earwigs, are often extensive and tucked away under the minute 

 elytra. The beetles often fly well. They are usually long and narrow, 

 and very active ; they live on carrion, snails, worms, other insects, fungi, 

 etc. A few species live in ants' nests. The larvae are active and cam- 

 podeiform ; their feet are terminated by a single claw. The pupae of some 

 are obtected, that is ensheathed in a hardened exudation which" fastens 

 all the appendages together. Ocypus and many others British. 



Fam. 20. Sphaeriidae. Minute. Eleven-segmented, clubbed antennae. 

 Three-segmented tarsi. Three visible abdominal sterna. Very small 

 beetles with but three or four species mostly found on mud. Sphaerius 

 acaroides occurs in the fens of Cambridgeshire. 



Fam. 21. Trichopterygidae. The smallest members of the Order. 

 Antennae slender, their apical j oints thickened. Tarsi with three segments. 

 Wings narrow and long, fringed with hairs. A widely distributed family 

 whose members live amongst moss and leaves. They are all very minute 

 and the smallest forms are the smallest of Insects. Nanosella fungi 

 measures but one-hundredth of an inch in length. There are some eighty 

 British species. 



Fam. 22. Hydroseaphidae. Very tiny, aquatic beetles with long 

 abdomens. Antennae have eight segments. Only a few American and 

 .South European species known. 



Fam. 23. Corylophidae. Minute with fringed short wings. Tarsi 

 with four segments but only three easily visible. A widely distributed 

 but small family of minute beetles, some of which live in thatches. 



Fam. 24. Scaphidiidae. Front coxae conical, hind coxae widely 

 Separated. Prothorax closely applied to the succeeding segments. Five 

 segments to the tarsi. This family is small and widely distributed, with 

 very active members which live among fungi. Scaphidium is British. 



Fam. 25. Synteliidae. Antennae clubbed. Front coxae transverse. 

 Labium prominent. Five visible abdominal sterna and eight or nine 

 terga. A widely distributed family of only five species which feed on sap 

 exuding from plants. 



