HYMENOPTERA. 101 



The male of this species resembles the female iu the form of 

 the abdomen and node of the peduncle, they are, however, 

 smoother and more highly polished ; all the specimens which I 

 have examined are of a paler colour, being more or less obscurely 

 ferruginous ; the head narrower than the thorax, the eyes large 

 and prominent, and the antennae three-fourths of the length of 

 the body. 



Genus 5. PLECTROCTENA. 



Head subquadrate ; antennae shorter than the head and thorax ; 

 the flagellum clavate, inserted very forward on the face near its 

 anterior margin on each side of a central protuberance, which is 

 advanced over and conceals the clypeus ; the anterior margin of 

 the latter widely emarginate ; eyes small and ovate, not promi- 

 nent, situated very forward on the sides of the head near the base 

 of the mandibles; mandibles elongate, very slightly bent and 

 crossing each other, their inner margin with a blunt tooth towards 

 their base; the labial palpi 4-jointed; the maxillary palpi 3- 

 jointed. Thorax oblong ; the calcar at the apex of all the tibiae, 

 pectinate within. Abdomen oblong, with a deep strangulation be- 

 tween the first and second segments ; the node subglobose. 



This subgenus of Ponera differs in such remarkable peculiari- 

 ties, and will not assimilate with any divisional group yet pro- 

 posed, that it must stand isolated for the present : the form of 

 the mandibles appears to indicate some peculiar economy ; the 

 small advanced eyes are also remarkable : the characters, being 

 drawn from a worker ant, will doubtless require hereafter some 

 additions and modifications. The beautiful pectination of the 

 tibial spurs is common to several of the Ponerida, but is some- 

 times only to be observed on the anterior legs, as in Ectatomma. 



1. PlECTROCTENA MANDIBULARIS. PI. VII. figs. 1-5. B.M. 



Worker. Length 5-7 lines. — Shining black : delicately and 

 not very closely punctured ; an impressed line runs upwards from 

 the anterior margin of the elevation between the antennae, half- 

 way towards the vertex ; the mandibles grooved longitudinally. 

 Thorax oblong, rounded in front, slightly narrowed and obliquely 

 truncated posteriorly, finely punctured, and the sides delicately 

 striated ; the tarsi with a fulvous pubescence, the anterior pair 

 densely pubescent beneath. Abdomen : the first segment finely 

 punctured, the node of the peduncle iucrassate, subglobose and 

 finely punctured. 



Male. Length 4 lines. —Black : the apex of the abdomen fer- 

 ruginous ; head narrower than the thorax, transverse, with the 



