_Worker._ Length 1-1/4 line. Black, smooth and shining; the vertex, thorax and nodes of the peduncle with an obscure ferruginous tinge; the antennae, tarsi, and articulations of the legs pale rufo-testaceous; the spines which arm the metathorax stout, elongate, and acute, with their apex pale testaceous. Abdomen heart-shaped and very acute at the apex. _Hab._ Aru. Gen. SOLENOPSIS, _Westw._ 1. SOLENOPSIS CEPHALOTES. _S._ pallide ferruginea; capite maxime in medio sulcato, abdomine apice fusco. _Worker major._ Length 2-1/2 lines. Pale ferruginous, with the anterior part of the face darker, the mandibles incrassate and very dark fusco-ferruginous; head very large and divided by a deep longitudinal channel, emarginate behind, nearly quadrate; the eyes small and placed forwards on the sides of the head. The metathorax truncate, not spined. Abdomen ovate, truncate at the base, its apex fuscous; the first node of the petiole compressed, its margin rounded above, the second node incrassate and subglobose; club of the antennae 2-jointed. _Worker minor._ Length 1-1/2 line. Of the same colour as the _worker major_, but with the head of the ordinary size and slightly narrowed behind, the mandibles of the same colour as the head; the legs and antennae longer, as well as the petiole of the abdomen; the body is very smooth and shining, the club of the antennae 2-jointed. _Hab._ Aru. Subfam. CRYPTOCERIDAE, _Smith_. Gen. MERANOPLUS, _Smith_. 1. MERANOPLUS SPINOSUS. _M._ castaneo-rufus; abdomine nigro, thorace sexspinoso; abdomine ovato. _Worker._ Length 1-1/2 line. Head and thorax rugose; the antennae and tarsi rufo-testaceous; the eyes rather prominent, the groove above them at the sides of the head extending backwards to the vertex. Thorax: the anterior margin curved forwards, the lateral angles produced into a bifurcate process on each side, behind the processes, slightly narrowed to the base of a long curved tooth; the posterior margin emarginate with a long sharp spine at each angle of the emargination; the node of the petiole globose. Abdomen black, smooth and shining. _Hab._ Aru. Fam. MUTILLIDAE, _Leach_. Gen. MUTILLA, _Linn._ 1. Mutilla Sibylla, _Smith, Proc. Linn. Soc._ ii. 86. 11 [Symbol: female]. _Hab._ Aru; Borneo; Celebes. 2. MUTILLA MANIFESTA. _M._ capite abdomineque nigris, thorace sanguineo-rubro, maris alis nigro-fuscis. _Female._ Length 4-3/4 lines. Head black and rugose. The thorax blood-red and coarsely rugose, its anterior margin widest and straight, the sides gradually narrowed to the apex in a slight curve; the lateral margins have two teeth not wide apart. Abdomen black, rugose, and slightly shining, with black pubescence above; on the under surface it is glittering silvery-white; the legs and sides of the thorax have a similar pubescence.