iv. The Cryptocerini are distinguished from other ants by their antennae being inserted at the sides of the head, where they are placed between ridges or in a groove into which they can be withdrawn; when in some cases they are entirely concealed. These ants assume a great variety of shapes and forms, some of which look almost as if they were the results of an extravagant imagination. The skeleton is usually much harder than it is in other {170}ants; the abdomen consists almost entirely of one very large segment, there being, however, three others visible at its extremity; these segments can be only slightly protruded, and the ants have no power of stinging. They are probably most of them arboreal in their habits. Nearly all of the known forms are exotic. According to the observations of Bates the species of the genus _Cryptocerus_ in the Amazons Valley may frequently be observed in dry open places on low trees and bushes, or running on branches of newly felled trees; they also visit flowers abundantly. The species generally are wood-borers, usually perforating the dead branches of trees. _C. atratus_ has been observed to construct its nests in the dead, suspended branches of woody climbers; a number of neatly drilled holes are all that can be seen externally; but, inside, the wood is freely perforated with intercommunicating galleries. Each community appears to consist of a single female and two kinds of workers; the latter in some species are quite unlike each other, differing in the form of the head, and in the armature of the thorax and nodes of the peduncle. The species of _Cryptocerus_ appear to be omnivorous, and are frequently attracted by the excrement of birds. The pupae are not enclosed in a cocoon. In the South of Europe two very minute ants, of the genera _Strumigenys_ and _Epitritus_, belonging to this family, are met with under very large stones partly embedded in the earth. They are of the greatest rarity. [Illustration: Fig. 74—_Cyrptocerus atratus_, worker. Amazons. The compressed first joint of the hind foot is shown at _a_ and _b_ in different positions.] SUB-FAM. 4. PONERIDES.—_Hind body elongate, furnished with one node at the base, and having also great capacity of movement between the first and second segments, between which there is usually a slight constriction. Sting well developed._