wheeler: ants of the genus formica. 381 



which has several of the characters of Proformica, is in general habitus 

 more like a true Formica. Emery ^ and I, however, have independ- 

 ently reached the conclusion that this ant is properly a Proformica. 



A study of our North American Formicae shows that F. pallide- 

 fulva sens lat. is even more worthy than Proformica of ranking as a 

 distinct subgenus, for the male differs from that of the other species 

 in much the same manner as does the male of Proformica, while the 

 worker in the structure of the thorax and antennae is even further 

 removed from the species of the subgenus Formica. I have therefore 

 erected a new subgenus, Neoformica, to include F. jmUidcfuha and 

 its various subspecies and varieties and F. mold Wheeler. The latter 

 form is provisionally placed in this group because its male and female 

 phases are still unknown.^ 



It is possible, as Emery clearly showed, to separate the various 

 species of the subgenus Formica into groups. These are more sharply 

 defined in the present paper. The ri//a-like species with diminutive 

 females I regard as constituting a distinct group (microgyna group), 

 although I am unable to find any satisfactory worker characters on 

 which to base it. The exsecta group is so sharply defined as scarcely 

 to admit of discussion. I have expanded the sanguinea group by 

 including in it a number of species with notched clypeus though lack- 

 ing the parasitic or slave-making habits of the typical sanguinea. 

 These species may have to be placed in a group by themselves when our 

 knowledge of their sexual phases is more advanced. The rufa group, 

 especially in North x\merica, presents the greatest difficulties in the 

 delimitation of species. This was clearly recognized by Emery, who 

 would be the first to admit that his treatment of our rufa forms was 

 inadequate on account of the insufficient amount of material at his 

 disposal. I have endeavored to reduce the confusion by recognizing 

 the Eurasian truncicola as a distinct species and by referring to it a 

 number of forms {integroides, intcgra, and obscuriventris) which have 

 been hitherto regarded as subspecies or varieties of rufa sens. sir. 

 The habits of all these American forms agree very closely with those 

 of the Eurasian truncicola and differ from those of rufa and its sub- 



1 Der wanderzug der Steppen-u. Wiistenameisen von Zentral-Asien nach Siid- 

 Europa und Nord-Afrika. Zool. jahrb. Suppl., 1912, 15, p. 95-104. Emery's state- 

 ment refers only to F. lasioides, which in my opinion is merely a subspecies of neoga- 

 gates {vide infra). 



2 That the ethological affinities of Proformica and Neoformica with Formica sens, 

 str. are extremely close is shown by the fact that such form as P. neogagates and N. 

 incerta sometimes fxmction, either alone or in company with F. fusca, as slaves, or 

 auxiliaries of F. sanguinea. 



