WHEELER: ANTS OF THE GENUS FORMICA. 383 
of Formiea sens. str., 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. flori 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 specious, but a moment’s consideration 
shows its feebleness for, as Emery has pointed out, the mandibles of 
the male flort 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 ursprung des sozialen parasitismus, der sklaverei und der myrmeko- 
philie beiden 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. phaéthusa, 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. imparis 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. 
