iv AXTS MYRMICIDES 163 



S. testaccus is a weak little ant, and lives in small numbers in the 

 nests with T. caespitum, which it is said to greatly resemble in 

 appearance. The proportions of the forms of the two species 

 usually associated is peculiar, there being a great many workers 

 of T. caespitum both in the perfect and pupal states, and also all 

 the sexes of the Strongylognathus, of which, however, only a few 

 are workers. This would seem to suggest that S. testaceus attacks 

 and pillages the nests of T. caespitum in order to carry off worker 

 pupae, just as Polyergus rnfescens does. But the facts that S. 

 testaceus is a weaker Insect than the Tetramorium, and that only 

 a few of its worker-caste are present in a community where there 

 are many workers of the Tetramorium, seem to negative the view 

 that the latter were captured by the former ; and the mode in 

 which the associated communities of these two species are started 

 and kept up is still therefore in need of explanation. 



Strongylognathus liuberi is a much stronger Insect than its 

 congener, S. testaceus, and Forel has witnessed its attack on 

 Tetramorium caespitum. Here the raid is made in a similar 

 manner to that of Polyergus rnfescens on Formica ; the Tetramo- 

 rium is attacked, and its pupae carried off to the abode of the 

 Strongylognathus to serve in due time as its slaves. The man- 

 dibles of S. liuberi, being similar in form to those of Polyergus 

 rnfescens, are used in a similar manner. 



Although T. caespitum is common enough in South-East Eng- 

 land, it is to be regretted that none of the guests or associates we 

 have mentioned in connection with it occur in this country. It 

 is a most variable species, and is distributed over a large part of 

 the globe. 



Our British species of Myrmicides, about ten in number, 

 all belong to the group Myrmicini ; none of them are generally 

 common except Myrmica rubra, which is a most abundant Insect, 

 and forms numerous races that have been considered by some 

 entomologists to be distinct species ; the two most abundant of 

 these races are M. ruginodis and M. scabrinodis, which sometimes, 

 at the time of the appearance of the winged individuals, form vast 

 swarms. 



The tiny Monomorium pharaonis is a species that has 

 been introduced into Britain, but now occurs in houses in 

 certain towns ; it sometimes accumulates on provisions in such 

 numbers as to be a serious nuisance. Seventeen thousand 



