128 
William Morton Wheeler 
Described from a single specimen (without a number) in the 
Geolog. Inst. Koenigsberg Coli. This specimen is well-preserved and 
shows the posterior portion of the head, antennse, thorax and petiole 
very clearly. In the structure of these parts and in its pilosity it is 
evidently quite distinct from either F. fiori or phaethusa. 
With the discovery in the Baltic amber of three new species of 
Formica, one allied to the recent cinerea and two belonging to the rufa 
group, Wasmann’s recent speculations concerning the phylogeny of 
the genus are deprived of their last slender Support and fall to the 
ground, because it can be no longer asserted that F. fiori, which is 
very closely related to the recent F. fusca, is the oldest and most primi- 
tive species and that F. rufa and sanguinea are descended from such 
a form. Hot only is it clear that F. rufa may be quite as old as 
F. fusca or even older, but it is even probable that F. phaethusa and 
clymene were temporary social parasites on the much more abundant 
F. fiori of the Oligocene, in precisely the same manner as the recent 
F. truncicola and rufa are temporary parasites on F. fusca. The six species 
of Formica now known from the Baltic amber not only show very 
clearly that the genus comprised a number of highly differentiated 
species as far back as the Lower Oligocene, but that even species of 
the F. rufa group, if they really originated in Horth America as Emery 
and I have given reasons for supposing, must have migrated into 
Eurasia before early Tertiary times. 
Formica constricta (Mayr). (Fig. 61.) 
Camponotus constrictus Mayr, Beitr. Naturk. Preuss. I, 1868, p. 29, Taf. I, Fig. 11 
Dalla Torre, Catalog. Hymen. VII, 1893, p. 226; Ern. Andre, Bull. 
Soc. Zool. France, XX, 1895, p. 82; Handlirsch, Foss. Insekt. 1908, p. 867. 
Worker. Length 5 — 10 mm. 
Body slender. Head longer than broad, convex above, a little 
broader behind than in front, without distinct posterior corners, with 
rounded posterior border and nearly straight. sides. Eyes large ellip- 
tical, moderately convex, behind the middle of the head. Ocelli large 
and distinct. Mandibles with 7 unequal teeth as in many other species 
of the genus. Clypeus somewhat depressed, but strongly carinate, its 
anterior border produced, indistinctly sinuate in the middle and on 
each side. Clypeal and antennary fovese confluent. Frontal area 
distinct, triangulär. Frontal carinse long, straight and parallel behind, 
somewhat sygmoidal in front. Antennse inserted very near the posterior 
clypeal border, very long and slender; scapes straight at the base, not 
enlarged towards their tips, extending more than half their length 
