similar to the larvae of the ants; although it possesses legs it scarcely uses them: its development takes place with extraordinary rapidity, two days, at most, being occupied in the egg, and the larva completing its growth in fourteen days. Wasmann seems to be of opinion that the ants scarcely distinguish between the beetle-larvae and their own young; one unfortunate result for the beetle follows from this, viz. that in the pupal state the treatment that is suitable for the ant-larvae does not agree with the beetle-larvae: the ants are in the habit of digging up their own kind and lifting them out and cleaning them during their metamorphosis; they also do this with the beetle-larvae, with fatal results; so that only those that have the good fortune to be forgotten by the ants complete their development. Thus from thirty _Lomechusa_ larvae Wasmann obtained a single imago, and from fifty _Atemeles_ larvae not even one. Many other Staphylinidae are exclusively attached to ants' nests, but most of them are either robbers, at warfare with the ants—as is the case with many species of _Myrmedonia_ that lurk about the outskirts of the nests—or are merely tolerated by the ants, not receiving any direct support from them. The most {227}remarkable Staphylinidae yet discovered are some viviparous species, forming the genera _Corotoca_ and _Spirachtha_, that have very swollen abdomens, and live in the nests of Termites in Brazil:[106] very little is, however, known about them. A very large and powerful Staphylinid, _Velleius dilatatus_, lives only in the nests of hornets and wasps. It has been supposed to be a defender of the Hymenoptera, but the recent observations of Janet and Wasmann make it clear that this is not the case: the _Velleius_ has the power of making itself disagreeable to the hornets by some odour, and they do not seriously attack it. The _Velleius_ finds its nutriment in larvae or pupae of the wasps that have fallen from their cells, or in other organic refuse. The larvae of Staphylinidae are very similar to those of Carabidae, but their legs are less perfect, and are terminated only by a single claw; there is no distinct labrum. The pupae of some are obtected, _i.e._ covered by a secondary exudation that glues all the appendages together, and forms a hard coat, as in Lepidoptera. We have about 800 species of Staphylinidae in Britain, and it is probable that the family will prove one of the most extensive of the Order. It is probable that one hundred thousand species or even more are at present in existence. FAM. 20. SPHAERIIDAE.—_Very minute. Antennae eleven-jointed, clubbed. Tarsi three-jointed. Abdomen with only three visible ventral segments_. This family includes only three or four species of Insects about 1/50 of an inch long. They are very convex, and be found walking on mud. _S. acaroides_ occurs in our fens. Mr. Matthews considers that they are most nearly allied to Hydrophilidae.[107]