TETRAMORIUM. 169 



the former were probably eventually eaten, as I have been unable 

 to detect any affinis workers, though a number of interruptus 

 workers have been reared. Eggs were laid by the interruptus 

 females on May 25th, 1914. 



On July 24th, 1914, a number of colonies of interruptus were 

 again observed in the New Forest one of these, which contained 

 many males and winged females, was found in the centre of a 

 strong colony of Myrmica scabrinodis v. sabuleti situated in a 

 mound and workers, larvae, and pupae were brought home and 

 placed in the outer part of the 1913 nest. The new workers entered 

 the nest, breaking through the earthen wall constructed by the old 

 inhabitants of the nest and joining forces with them. No fighting 

 took place and the ants have formed one colony. 



TETRAMORIUM Mayr. 



[rtTpa, four ; fj.6pLov, parts (i.e. the joints of the maxillary palpi).] 



Type : Formica caespitum L. (Girard, 1879). 



This genus is distributed over the whole world, and contains 

 many aphidicolous species. Tetramorium is essentially African, 

 but many species have reached India and New Guinea ; Europe has 

 probably acquired its representatives from Southern Asia, and 

 only a few more or less aberrant species are present in America. 

 Two cosmopolitan forms, which have been carried all over the 

 world by commerce, occur in Britain in hot-houses. 



Girard [Traite. Elem. Ent. 2 1016 (1879)] cites Formica caespitum 

 L., as the type of this genus, in which he is followed by Bingham 

 [Faun. Brit. India Hym. 2 175 (1903)], and Wheeler [Ann. New 

 York Acad. Sc. 21 173 (1911) : 23 79 (1913)]. 



$ Head quadrangular ; clypeus triangular, with its posterior margins 

 raised on each side and forming a projecting carina which borders the antennal 

 cavities anteriorly ; frontal carinae projecting, short, wide apart and some- 

 what divergent posteriorly ; frontal area not sharply denned ; mandibles 

 broad, with five to seven teeth on the terminal margins ; maxillary palpi 

 four- jointed ; labial palpi three- jointed ; antennae twelve- jointed, funiculus 

 with the last three joints forming a club, which is about as long as the rest of 

 the joints of the funiculus taken together, last joint of club longer than the 

 two preceding taken together. Thorax short ; pronotum broad anteriorly, 

 with distinct anterior angles ; somewhat depressed between the mesonotum 

 and the epinotum ; epinotum armed with two short spines, or pointed 

 teeth. Petiole cylindrical anteriorly, nodiform posteriorly ; post-petiole 

 transverse, broader than petiole ; gaster oval ; sting large. 



$ Size large, two or three times that of the ^. Characters as in the ^, 

 epinotal spines stouter, gaster longer and more robust. Wings : fore-wings 

 with one cubital cell and one discoidal cell. 



<J Head smaller than in the $ ; mandibles flat, terminal margin dentate ; 

 maxillary palpi four- jointed ; labial palpi three- join ted ; antennae ten- 

 jointed, scape short, funiculus with the second joint long, longer than scape. 

 Thorax : mesonotum with Mayrian furrows ; epinotum slanting, armed with 

 two very feeble teeth, or tubercles. Wings as in the $. Size a little smaller 

 than in the <j>. 



