SMITH ON HTMENOPTERA OF ARU ISLANDS, 141 



in front, or very slightly curved, with the lateral angles acute ; the 

 thorax is rounded above, and not mai-gined at the sides ; the meta- 

 thorax armed with two long, stout, acute compressed spines; the 

 spines divergent, as well as two on the scale of the petiole, which are 

 long and very acute. Abdomen globose. 

 Hab. Am. 



.9. PoLYRHACHis GEOMETRicus. P. niger ; antennarum apice, tibiis 

 tarsorumque apice ferrugineis, thorace circulariter striato. 



Worker. Length 2 lines. Black ; the apical joints of the flagellum, 

 the anterior legs, the anterior and intermediate tibiae, and the apical 

 joints of the tarsi pale ferruginous ; the extreme base of the anterior 

 tarsi black. Thorax rounded above, not margined, gradually narrowed 

 posteriorly ; the prothorax of the same width as the head, its lateral 

 angles toothed; the disk with a circular striation. Abdomen globose 

 and pubescent; the scale of the petiole compressed, its superior 

 margin rounded, and with four minute teeth. 



Hah, Aru. 



10. PoLYRHACHis iRRiTABiLis. P. uigcr, pube pallide aurea ves- 

 titus ; thorace quadridentato, petioli squamula bidentata. 



Female. Length 6^ lines. Black, and densely clothed with short pale 

 golden pubescence ; all parts of the insect sprinkled with erect cine- 

 reous hairs; the mandibles shining black, the palpi pale testaceous ; 

 the head elongate, the eyes placed high on the sides of the head, fer- 

 ruginous and very prominent. Thorax elongate-ovate; the pro- 

 thorax with a short, stout, acute tooth on each side, slightly curved 

 and directed forwards ; the metathorax with a similar tooth on each 

 side directed backwards ; the wings subhyaline, the nervures fuscous ; 

 the legs fusco-ferruginous, the femora and coxae brightest. Abdomen 

 ovate ; the scale incrassate, armed above with two stout acute teeth. 



Hab. Aru. 



This is probably the female of P. sexspinosus. 



\\. PoLYRHACHis L^vissiMus. P. niger, laevis uitidusquc ; mcta- 

 thorace bispinoso, petioli squamula quadrispinosa, pedibus ferrugineis. 

 Worker. Length 2| lines. Black, very smooth and shining ; the 

 legs ferruginous, with the coxae, articulations, and the tarsi black. 

 The thorax not flattened above, or margined at the sides ; the division 

 between the pro- and mesothorax distinct, that between the meso- 

 and metathorax not discernible, the latter with two erect acute 

 spines ; the scale of the petiole with four short acute spines. Abdo- 

 men globose. 

 Hab. Aru. 



This species is very like P. mucronatus ; on close examination, how- 

 ever, it is seen to be very distinct : it may be at once distinguished by its 

 larger head, which is wider than the thorax, rounded behind the eyes, 

 and widely emarginate behind. 



