ARMY ANTS IN BRITISH GUIANA. 315 



is fully three times as long as high, its dorsal outline straight, its 

 dorsal svu"face flattened. Promesonotal, mesometanotal and meta- 

 epinotal sutures indicated by impressed lines. Pronotum as long as 

 broad, its anterior border marginate at the neck; mesonotum slightly 

 longer than broad, its anterior border strongly arcuate, its posterior 

 border less so; metanotum in the form of a very short, transverse, 

 arcuate band; epinotum broader than long, with rounded rectangular 

 posterior corners, its surface broadly impressed in the middle and 

 with a distinct, median, longitudinal groove on its anterior half; 

 the base in profile longer than the straight declivity with which it 

 forms an obtuse angle. Petiole as high as the epinotum, but much 

 narrower, from above transversely oblong, with rounded sides, about 

 Ij times as broad as long, broadly impressed in the middle; the 

 ventral portion protruding downward and forward as a thick con- 

 vexity. Gaster long and rather slender, though more than twice as 

 broad as the petiole, its anterior segment rectangular from above; 

 pygidium large, con^-ex, bluntly pointed and entire behind; hypo- 

 pygium angularly excised in the middle and terminating in two mem- 

 branous, rather blunt points. Sting small, partly exserted. Legs 

 rather short; claws simple. Stigmata of the thorax, petiole, post- 

 petiole and gaster large. 



Head, thorax and petiole nearly opaque, very finely shagreened, 

 densely and rather coarsely punctate; gaster shining, with much 

 smaller, shallower and more scattered punctures, except on the first 

 segment (postpetiole), which approaches the petiole in sculpture. 



Hairs yellowish, short, erect, abundant on the head, thorax, petiole 

 and appendages, much shorter and sparser on the gaster; mandibles, 

 clypeus, gula and scapes also with numerous long, flexuous hairs of 

 uneven length. 



Rich ferruginous red; antennae and legs slightly paler and more 

 yellowish; pygidium brown. 



Male (Fig. 8c). Length 9.3 mm. 



Closely resembling the male of opacithorax Emery but slightly 

 smaller and distinctly more slender. Eyes and ocelli even smaller. 

 Mandibles much narrower and less expanded in the middle. Antennse 

 more slender. Thorax shorter; petiole shorter in proportion to its 

 width. Terminal points of subgenital plate longer and less curved. 

 Sculpture, pilosity and color much as in opacithorax, except that the 

 thorax is not shining but opaque and more densely and more coarsely 

 punctate. The scapes and mandibles are black, not red as in opaci- 

 thorax. 



