1. Plectroctena mandibularis ^HNS. Pl. VII. figs. 1-5. B.M.

Worker. Length 5-7 lines.-Shining black: delicately and not very closely punctured; an impressed line runs upwards from the anterior margin of the elevation between the antennae, halfway towards the vertex; the mandibles grooved longitudinally. Thorax oblong, rounded in front, slightly narrowed and obliquely truncated posteriorly, finely punctured, and the sides delicately striated; the tarsi with a fulvous pubescence, the anterior pair densely pubescent beneath. Abdomen: the first segment finely punctured, the node of the peduncle incrassate, subglobose and finely punctured.

Male. Length 4 lines. -Black: the apex of the abdomen ferruginous; head narrower than the thorax, transverse, with the vertex slightly narrowed behind the eyes; shining and delicately punctured; the antennae inserted in front of two elevated processes, the clypeus widely emarginate; mandibles short, not toothed and blunt at their apex. Thorax rugose, the disk with a mixture of confluent punctures and striae; the mesothorax with two deeply impressed oblique channels running inwards and uniting at the base of the scutellum; the wings subhyaline and iridescent, the nervures testaceous, the stigma fuscous. Abdomen: the three apical segments ferruginous, of the same form as in the female, the node of the petiole also similar. The worker not known.

Hab . Port Natal.

The sexes, taken in coitu by Herr Gueinzius, have been received from Port Natal; he says, " solitary; I have not been able to find its nest."