11. Crematogaster arboreus ^HNS. Pl. XIV. Nest. B.M.

Worker. Length 2 lines.-Pale ferruginous, with very thinly scattered short glittering hairs: the head subovate, slightly emarginate behind, delicately striated longitudinally, the mandibles with four strong acute teeth; the antennae, tarsi, and apex of the abdomen more or less fuscous. Thorax flattened on the disk, deeply strangulated between the meso- and metathorax, with the latter armed with two acute spines. Abdomen: the first node of the peduncle, viewed in front, pear-shaped, with the broad end downwards; the second node ovate, with a deeply impressed line above.

Hab. Port Natal.

The nest of this species, of which a figure is given, was sent to England by Herr Gueinzius from Port Natal: a number of specimens of the insect were found in the crevices and entrances to the nest; many individuals are of a paler colour than the one described, but all are of the same size, sex, and form.