446 .l.\TS. 



he found near Strasburg living with a small number of fusca workers. 1 

 These facts, taken singly are rather insignificant, but conjointly they 

 point very decidedly to the conclusion that most, if not all, the ants of 

 the rufa group are temporary parasites. 



3. The Formicae of the Exsecta Group. This group, which is char- 

 acterized by having the head of the worker and female deeply excised 

 behind, is represented in Europe by the typical F. c.vsccta, its subspecies 

 prcssilabris and F. snccica, a species recently discovered in Sweden by 

 Adlerz; in Xorth America by F. cxsectoidcs, its subspecies opacircntris 

 and F. nlkci. These ants build mound nests, often several to a colony, 

 and sometimes of large size, especially in America ( Figs. 109 and 

 181). The females are large in our forms, but smaller in cxsccta 

 and pressilabris, and scarcely larger than the workers in snccica. 

 There is indirect evidence that all of these ants, except ulkci, which 

 has not yet been observed in nature, are temporary parasites. In his 

 " Fourmis de la Suisse " Forel described two small mixed colonies of 

 c.rsccta-fnsca and two of exsectopressilabris-fusca. During the sum- 

 mer of 1907 I also found a mixed colony of the latter composition, 

 occupying a single small mound, on the slopes of Monte Generoso. 

 Similar mixed colonies of exsectoides and subsericea have been 

 repeatedly observed in the Eastern States. Forel observed one at 

 Hartford, Conn., and the late Rev. P. J. Schmitt found five near 

 Beatty, Pa. These invariably contained queens of cxsectoidcs only, 

 and all were obviously incipient, since they comprised not more than 

 fifty workers, both species included. I have found two of these mixed 

 colonies at Colebrook, Conn., and have observed the behavior of an 

 c.vscctoidcs queen when she is introduced into a colony of subs.cncca 

 workers. She is very passive and conciliatory and in one of my experi- 

 ments was readily adopted by the alien colony. Considering the close 

 taxonomic affinities of F. nlkci to exsectoides and the diminutive 

 stature of the female snccica, we may assume that these species can 

 hardly differ in their habits from the other members of the cxsecta 

 group. 



4. Bothriomyrmex. Among the mixed colonies recorded by Forel 

 ( 18/4 ) there was one composed of two species of Dolichoderine ants. 

 Bothriomyrmex meridional-is and Tapinouia crraticnin, which he found 

 on the Borromean Islands in the Lago Maggiore. This colony, like the 

 colonies of truncicola-fusca and exsecta-fnsca above mentioned, had 



1 During the past summer ( 1909) I found three mixed colonies of F. rufa 

 and fusca, which show very clearly that the former is a temporary parasite like 

 cotisocians. Two of these, discovered in the Turtman Valley, in Switzer- 

 land, each consisted of a rufa queen and several fusca workers, the third, found 

 at Zennatt. contained besides a rufa queen a few workers of the same species. 



