128 William Morton Wheeler 



Described from a single specimen (without a number) in the 

 Geolog. Inst. Koenigsberg Coll. This specimen is well-preserved and 

 shows the posterior portion of the head, antennae, 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 phaetJiusa. 



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. Not 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 North 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 Mate, Beitr. Naturk. Preuss. I, 1868, p. 29, Taf. I, Fig. 11 $; 

 Dalla Torre, Catalog. Hymen. VII, 1893, p. 226; Erk. 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, triangular. Frontal carinae long, straight and parallel behind, 

 somewhat sygmoidal in front. Antennae 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 



