_Worker._ Length 3 lines. Obscurely ferruginous, the scape of the antennae, the base of the femora and the tibiae pale ferruginous; the base of the abdomen pale testaceous; the head and thorax with deep coarse longitudinal furrows; the flagellum blackish-brown towards its apex, with the extreme tip pale. Thorax: the anterior margin slightly rounded with the lateral angles very acute; the femora very thickly incrassate in the middle; the apex of the tibiae ferruginous. Abdomen smooth and shining; the basal half pale testaceous, the apical half and the following segments black; the nodes of the petiole rugose; the first node elongate, with a short acute tooth at the base above, and a blunt one beneath. _Hab._ Aru. Gen. MYRMICA, _Latr._ 1. MYRMICA PARALLELA. _M._ rufo-fulva; antennis pedibusque pallide testaceis; abdomine fusco-ferrugineo; capite thoraceque longitudinaliter striatis. _Worker._ Length 1 line. Head and thorax ferruginous and longitudinally and evenly striated; antennae and legs pale rufo-testaceous. Thorax margined at the sides, the disk slightly convex, the anterior margin transverse, the lateral angles acute; the metathorax with two short spines; abdomen dark fusco-ferruginous, the nodes of the petiole subrugose; club of the antennae 3-jointed. _Hab._ Aru. 2. MYRMICA SCABROSA. _M._ nigra; capite thoraceque scabrosis, metathorace bispinoso, abdomine ovato laevi. _Worker._ Length 1 line. Black; the head, thorax, and nodes of the petiole roughened; the mandibles, flagellum and tarsi rufo-testaceous; the lateral angles of the prothorax acute, the sides narrowed slightly to the base of the metathorax, the spines on the latter acute; nodes of the petiole globose. Abdomen ovate, smooth and shining; club of the antennae 3-jointed. _Hab._ Aru. 3. MYRMICA THORACICA. _M._ capite abdomineque nigris; antennis, mandibulis thorace pedibusque flavis. _Worker._ Length 3/4 line. Head and abdomen jet-black; the antennae, thorax, and legs of a clear honey-yellow; the mandibles of a more obscure yellow; the anterior margin of the thorax transverse, the lateral angles acute, narrowed from thence to the base of the mesothorax, the disk anteriorly slightly convex; the metathorax armed with two acute spines. Abdomen nearly round, and very smooth and shining; the first node of the petiole vertical anteriorly, and gradually rounded behind, the second node transverse, its anterior margin straight, the angles rounded, the sides narrowed towards the abdomen; the club of the antennae 3-jointed. _Hab._ Aru. The singular form of the thorax of this species, as well as the construction of the nodes of the petiole, appear to indicate an uncharacterized division of the genus _Myrmica_. 4. MYRMICA SUSPICIOSA. _M._ rufo-testacea, laevis, tota nitidissima nuda; mandibulis, antennis, pedum articulationibus tarsisque palles-centibus; metathoracis spinis minutissimis.