wheeler: ants of the genus formica. 383 



of Formica sens, sir., notably concerning fusca, rufa, and sanguinea. 

 Wasmann/ starting from purely ethological considerations, has en- 

 deavored to show that the rufa forms have arisen from fusca and 

 have in turn given rise to sanguinea. In support of this view he calls 

 attention to F. fiori of the Baltic amber and its very close resemblance 

 to the living fusca. The absence of rufa and sanguinea in the amber 

 seems to be taken to indicate that they had not yet been evolved from 

 fusca. This argument is very sp'ecious, but a moment's consideration 

 shows its feebleness for, as Emery has pointed out, the mandibles of 

 the male fiori are completely edentate like those of the modern fusca 

 and of many members of its group, whereas the males of sanguinea 

 and of many forms of the rufa group have distinctly dentate mandibles. 

 We cannot, therefore, derive these forms from fusca, since it would 

 be contrary to phylogenetic methods to assume the re-development of 

 denticles on the vestigial mandibles of the descendant of a form in 

 which the denticles had already completely disappeared in the early 

 Tertiary. There is, in fact, nothing to indicate that fusca is the type 

 of the most primitive and ancestral group of Formicae or that it is 

 older than sanguinea or rufa. Emery may be quite right in supposing 

 that these species are quite as old as fusca and that the conditions in 

 the amber may be due to sanguinea and rufa having their origin in 

 America, Eastern Asia, or the polar regions and not having entered 

 the Baltic region till after the amber fauna had become extinct.^ 



Our knowledge of the geographical distribution of the North Ameri- 

 can Formicae has been very imperfect heretofore, owing to the small 

 amount of material which has passed through the hands of myrmecolo- 

 gists. For this reason I have given prominence to the subject in the 

 present paper by citing all or nearly all the localities from which 

 I have seen specimens. These localities are sufficiently numerous, 

 at least in the case of the more common forms, to enable us to form a 

 fairly accurate conception of their geographical range. I could have 



1 Ueber den urspnmg des sozialen parasitismus, der sklaverei und der myrmeko- 

 pliilie bei den ameisen. Biol, centralbl., 1909, 29, p. 587 et seq. 



^ Since this paragraph was written I have discovered in addition to F. flori four 

 undescribed species of Formica in the Baltic amber. One of these, F. horrida, sp. nov. 

 is closely related to cinerea, another, F. phaethusa, sp. nov. to truncicola, another, 

 F. clymene, sp. nov., to rufa, and the fourth, F. strangulata, sp. nov., in the peculiar 

 structure of its thorax, recalls certain species of Prenolepis (e. g. P. imparls Say). 

 I find also that the ant described by Mayr as Camponotus constrictus may be more 

 properly regarded as an aberrant Formica. These six species show very clearly that 

 the genus Formica was quite as highly specialized in the early Tertiary of Northern 

 Europe as it is at the present time, and that speculations, like those in which Wasmann 

 has been indulging, are utterly futile and misleading. 



