19. Atta vigilans ^HNS. B.M.

Worker. Length 2 lines.-Ferruginous, with the abdomen fuscous, and its base more or less pale. Head very largely developed, oblong, with a deep emargination behind, and a central longitudinal channel extending to the clypeus; the posterior half of the head, the clypeus and mandibles, smooth and shining, the latter with a few scattered punctures; the anterior margin of the face and the inner margin of the mandibles blackish; the anterior half of the face striated. Thorax smooth and shining; a deep strangulation between the meso- and metathorax, the latter with two short acute spines. Abdomen ovate and slightly pubescent.

Hab. Australia (Melbourne).