2. Polyrhachis compressicornis ^HNS.

P. niger et vestitus pube cinerea; thoraee spinis duabus acutis antice armato; abdominis squamula spinis duabus brevibus armata; pedibus ferrugineis.

Female. Length 51/2 lines. Black and densely clothed with cinereous pile, which has a silvery brightness in certain lights; the mandibles shining black, and longitudinally striated; the antennæ inserted at the sides of two prominent carinæ; the scape compressed, much broader than usual, with the apex widest and thinly covered with short pale glittering pubescence. Thorax: the spines at the lateral angles of the prothorax short, stout, and acute; the mesothorax very convex, with an abbreviated shining carina in the middle anteriorly; the metathorax transverse, abruptly truncated, slightly concave in the middle above; the legs ferruginous, with their articulations and tarsi fuscous. Abdomen ovate; the peduncle subtriangular, a stout, short, acute spine at the lateral angles.

Worker. Length 41/4 lines. Only differs in having the thorax flattened above, with the lateral margins slightly raised; the scape of the antennæ compressed, as in. the female.