:\\2 FORMICID^. 



Gemis MYRMECOCYSTUS. 



Formica, pt., Fabr. Maul. Ins. i (17S7), p. ?,0^, i} . 



IMyrmecncystus, TfV.s?/;. liiill. Acad. <Sc. liruv. v ClftOS), p. 770. 



( "ittaglypliis, J'V>V.<t/. Terh.Nat. Ver. Pirnsx. JiliciiiL vii (l^-")0), p. -lO.'T. 



Type, ^f. vH-lJif/ent, Lljive. from Amcrici. 



Banr/e. Both heniisphores. 



^ . Head without the mandibles quadrangular, not emarginatc 

 posteriorly, the sides straight or very slightly convex ; mandibles 

 comparatively large, strongly dentate, the apical tooth remarkably 

 long, curved and acute ; maxillary palpi (i-jointed, veiy long, the 

 .'Jrd and 4th joints the longest, the latter twice as long as the 5th 

 and arched ; labial palpi 4-jointed as in Formica ; clypeus convex,. 

 its anterior margin slightly arched; frontal area triangular, with 

 the clypeal-frontal sutiu'e distinct; antenual carinie very short, 

 |)arallel ; antenna^ springing from immediately behind the posterior 

 border of the clypeus, 12-iointed, filiform : eyes of moderate size, 

 oval, })laced well above the middle line of the head ; ocelli present. 

 Thorax viewed from the side constricted in the middle, saddle- 

 shaped, the sutures well-marked ; pronotum convex ; mesonotum 

 long, narrow, rounded above : metanotum short, gibbous ; legs 

 long and slender. Pedicel one-jointed, node rounded, not nuu-h' 

 rais(Kl ; abdomen somewhat short, oval, capable in the typical 

 species, which is American, of immense dilatation. 



5 . Similar to the ^ . Wings short, hyaline, the nervures 

 thick, W'ith one cuhitnl and one small, frequently incomplete, 

 discoidal cell. 



(S . Head smaller than in the ^ ; mandibles narrow, indistinctly 

 bidentate ; antenna^ 13-jointed, the scape long. Thorax com- 

 pressed ; pronotum slightly concave in the middle. Xode of the 

 pedicel q\iadrangular ; abdomen cylindrical. Genitalia very large, 

 the pencili wanting, but the lamiuic present : the external genital 

 plate bearing an appendix on the inner side. 



Only a single species ( ^ only known), that differs sHglitly but 

 constantly from the European and North African form, is found 

 within our limits. 



352. Myrmecocystus setipes. Font. 



Mvriuecocvsliis viaticiis, race setipes, Forel, Joiir. linvih. y. 7A. 

 ■ Soc. vii'i (1894), p. 401, ^ . 



^ . Head, thorax, legs nnd node of pedicel dark red. abdomen 

 black; the legs of a darker shade than the thorax, almost black. 

 I'ilosity on the head, thorax and abdomen sparse, confined to a 

 lew scattei'ed erect hairs, most numerous on the underside of the 

 abdomen ; legs densely setose and spinous : pubescence extremely 

 minute and tine, with a silvery glint, hut giving the head, thorax 

 and Jibdomcsn a dull subopaque ap])earance. Fov the rest the 

 chai-acters of the genus. 

 LcHith. ^ 10-1^2 mm. 



