TETRAMOEIUM. 175 



Genus TETRAMORIUM. 



581. 

 p. 



Formica, pt., Linn. Syst. Nat. ed. 10 (1758), p. 



Myrmica, pt., Lair. Hist. Nat. Ins. xiii (1805), 



Tetramorium, Mayr, Verh. zool.-bot. Ges. Wien, v (1855), p. 423. 



Xiphomyrmex, Ford, Mittheil. Schweiz. ent. Ges. vii (1887), p. 385. 



? Rhoptromyrmex *, Ford, Rev. Suisse Zool. x (1002), pp. 231 & 232. 



TVpe, T. ccespitum, Linn., from Europe. 

 Range. Both hemispheres. 



. Head generally more or less rectangular, with always a 

 distinct posterior margin ; mandibles broad, with from 57 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 ; antennal carinse short, 

 wide apart; antennae stout, 11- or 12-jointed, 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 more 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. 



d 1 . Head much smaller than in the $ , eyes and antennae large 

 and prominent ; mandibles flat, the masticatory margin dentate ; 

 antennae 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 converging 

 posteriorly ; metanotum truncate posteriorly and bidentate. 



Key to the Species. 

 A. Antennae 12-jointed. 



a. First joint of pedicel with an appendix 



beneath. 

 '. Head and thorax shining, very feebly 



longitudinally striate .............. T. wroughtoni, p. 177. 



b'. Head and thorax subopaque, densely 

 longitudinally striate, reticulate be- 

 tween striae ...................... 7'. rothneyi, p. 177. 



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

 I cannot find it characterized in any publication. 



