70 loitMn jD.i:. 



long, filifonii, the scape extended beyond the top of the head. 

 Thorax above rounded, shghtly compressed posteriorly, pronotum 

 strongly convex and as broad as the head ; pro-mesonotal suture 

 always distinct ; legs long and stout ; femora and tibiic cylin- 

 drical, claws simple. Pedicel oue-jointed, the node on a level 

 with or higher than the nietanotum, arched and generally very 

 convex in front, flat or a little concave posteriorly, above always 

 armed with two spines ; abdomen cylindrical, the constriction 

 between the basal two segments Mell-marked. Heaff, thorax and 

 jtedkel alivaj/s, and a portion of the abdomen also in the majority of 

 species, very heautifully and rer/alarly striate. 



(S . Similar to the ^ but more elongate. Head globose, wider 

 than the thorax ; mandibles short, cylindrical, acutely pointed at 

 apex ; antenna* filiform, scape very short, about half the length of 

 2Md joint of the fiagellum ; eyes and ocelli large and very prominent, 

 the space between the latter equal to the space bet\Aeen the orbit 

 of the eye and the lateral ocelli ; thorax very gibbous, the meso- 

 notum with a Y'^'^^^P'^*^^ furrow ; the scutellum large, convex, 

 separated from the mesonotum by a crenulate transverse impressed 

 line ; postscutellum and metanotum depressed, oblique, rounded 

 above ; legs very slight, elongate, femora slightly compressed, claws 

 simple. Xode of the pedicel more or less conical, a little flat 

 above, vnthont sjyines • abdomen elongate, rather massive for males. 

 The beautiful regular striae on the head, thorax and pedicel, con- 

 spicuous in the > feeble and not distinct. 



2 . Unknown *, 



Mr. Rothney (Tr. Ent. Soc. 1S89, p. 361) writes very fully on 

 the habits of D. vagans. Smith. I agree with him that the species 

 of this genus are by far the most intelligent of all Oriental ants. 



Ki'y to the Species. 



A. First abdominal segmout not striate. 



o. Node of pedicel very strongly laterally 



compressed, much longer than broad . . I), scalpralum, p. 77. 

 h. Node of pedicel not laterally compressed, 



quite as broad as long T). cyainvcntre, p. 78. 



B. First abdominal segment striate. 



a. Pronotum longitudinally striate IJ. a-^samense, p. 79. 



b. Pronotum with trans^•ersely arched strife, 



which are more or less concentric au- 

 teriorh'. 

 a'. First abdominal segment with the striae 



anteriorly in concentric arches, in the 



middle divergent I), ceijloitenxe, p. 70. 



* In vol. xii, p. 750, of the Jour. Bomb. N. H. Soc. I gave an account of the 

 finding of an ant I tliought was the 5 of D. vagans, Smith. I regret to say 

 tliat 1 was niietakcu : furtlier examination of the one specimen I kept has 

 sliown it to be only a large (T ; tbe 5 of Diacam7na remains, therefore, still 

 undiscovered. 



