20. Formica irritans ^HNS.

F. nigra; antennis, thorace pedunculisque squama ferrugineis.

' Worker. Length 6 lines. Head and abdomen nigro-fuscous; antennae, thorax, and scale of the abdomen, as well as the legs, ferruginous. Elongate and slender, the head ovate; the apex of the scape ferruginous; the clypeus and mandibles dark rufo-piceous. The thorax elongate, compressed, with the prothorax slightly dilated at the sides. Abdomen ovate: the scale incrassate, rounded anteriorly, and truncate behind; the entire insect thinly sprinkled with erect, long, pale pubescence.

Worker ( minor ^HNS). Length 3 lines. This only differs in having the antennae entirely pale ferruginous.

Hab. Borneo (Sarawak).

This is probably the worker of Formica diligens ^HNS.