Scarcely anything is known as to the lives of either the cave-Silphidae or the myrmecophilous forms. The larvae of several of the larger forms of Silphidae are well known, but very little has been ascertained as to the smaller forms. {222}Those of the burying-beetles have spiny plates on the back of the body, and do not resemble the other known forms of the family. The rule is that the three thoracic segments are well developed, and that ten abdominal segments are also distinct; the ninth abdominal segment bears a pair of cerci, which are sometimes elongate. Often the dorsal plates are harder and better developed than is usual in Coleopterous larvae. This is especially the case with some that are endowed with great powers of locomotion, such as _S. obscura_ (Fig. 104). The food of the larvae is as a rule decomposing animal or vegetable matter, but some are predaceous, and attack living objects. The larger _Silpha_ larvae live, like the _Necrophorus_, on decomposing animal matter, but run about to seek it; hence many specimens of some of these large larvae may sometimes be found amongst the bones of a very small dead bird. We have found the larva and imago of _S. thoracica_ in birds' nests containing dead nestlings. _S. atrata_ and _S. laevigata_ make war on snails. _S. lapponica_ enters the houses in Lapland and ravages the stores of animal provisions. _S. opaca_ departs in a very decided manner from the habits of its congeners, as it attacks beetroot and other similar crops in the growing state; it is sometimes the cause of serious loss to the growers of beet. The larvae of the group Anisotomides are believed to be chiefly subterranean in habits; that of _A. cinnamomea_ feeds on the truffle, and the beetle is known as the truffle-beetle. [Illustration: Fig. 104—A, Larva of _Silpha obscura_. Europe. (After Schiödte). B, _Ptomaphila lacrymosa_, Australia.] The number of species of Silphidae known must be at present nearer 900 than 800. Of these an unusually large proportion belong to the European and North American regions; Silphidae being apparently far from numerous in the tropics. Rather more than 100 species are natives of Britain. The family reappears in considerable force in New Zealand, and is probably well represented {223}in South Australia and Tasmania. The most remarkable form known is perhaps the Australian genus _Ptomaphila_ (Fig. 104, B). The classification of the family is due to Dr. Horn.[101] The only change of importance that has since been suggested is the removal of _Sphaerites_ from this family to Synteliidae. Anisotomidae and Clambidae have been considered distinct families, but are now included in Silphidae.