TETRAMOEIUM. 175 



Genus TETRAMORIUM. 



Formica, pt., Linn. Si/st. Nat. ed. 10 (1758), p. 581. 

 Myriuica, pt., Lrdr. Hist. Xat. Ins. xiii (1805), p. 259. 

 Tetraniorium, Mayr, Vorh. zool.-hot. Ges. Wien, v (1855), p. 423. 

 Xiphomvrmex, Forel, MittheU. Schweiz. ent. Ges. vii (1887), p. 385. 

 ? Pthoptromyrmex *, Furel, Rev. Suisse Zool. x (1002), pp. 231 .*t 232. 



Tvpe, T. ca'spitum, Linn., from Europe. 



Range. Both hemispheres. 



^ . Head generally more or less rectangular, with ah^ays a 

 distinct posterior margin ; mandibles broad, with from 5-7 teeth ; 

 maxillary palpi 4-, labial palpi 3-jointed ; clypeus triangular, the 

 apex posteriorly rounded between the bases of the antennae, the 

 anterior margin more or less transverse ; antenual cariuse short, 

 wide apart; antennae stout, 11- or 12-iointed, club of flagellum 

 formed of the apical three joints, which together are as long as 

 the remainder of the flagellum ; eyes rather small, lateral, round. 

 Thorax short, often arched from front to back ; pronotum seen 

 from above broad anteriorly, with the anterior lateral angles 

 prominent : thorax more or less narrowly emarginate at the 

 meso-metanotal suture : metanotum armed at the posterior 

 lateral angles of its basal portion with two spines or teeth ; 

 legs moderately stout. Pedicel : the nodes more or less rounded ; 

 the 1st node petiolate anteriorly, the front curved inwards ; 2nd 

 node generally a little broader than the 1st ; abdomen oval. 



2 . Closely resembles the ^ , but is much larger ; the head, 

 pedicel and abdomen as in the ^ , the last moi'e massive and 

 longer. Thorax massive, deep, with the mesonotum gibbous, 

 convex ; metanotum armed with two spines posteriorly as in 

 the ^ , but stouter. Fore wing with one cubital and one discoidal 

 cell. 



(S . Head much smaller than in the $ , eyes and antennae large 

 and prominent ; mandibles flat, the masticatory margin dentate ; 

 antennaj 10 -jointed, the scape short, not longer than the 2nd joint 

 of the flagellum. Thorax short and massive, the disc of the 

 mesonotum slightly convex, with two impressed lines convei'ging 

 posteriorly ; metanotum truncate posteriorly and bidentate. 



Keif to the Species. 



A. Antennae 12-jointed. 



a. First joint of pedicel with au appendix 

 beneath. 

 a'. Head and thorax shining, very feebly 



longitudinally striate T. icrouf/ldoni, p. 177. 



V . Head and thorax subopaque, densely 

 longitudinally striate, reticulate be- 

 tween strias T. rothneyi, p. 177. 



* Beyond the casual allusion to this genus or subgenus as quoted above. 

 I cannot find it characterized in any publication. 



