The Ants of the Baltic Amber. 
119 
K 903, K 4198, K 877, K 4451, K 868 etc.), one worker in the Berlin 
Museum and 12 workers in the Haren Coli. (200, 221, 254, 749, 1842, 
1075, 1736, 1875 etc.). 
The two pseudogynes are interesting as showing that an anomaly 
which today occurs most commonly in species of the genus Formica , 
occasionally made its appearance as far back as Lower Oligocene times 
and in the genus Prenolepis. Emery has also described and figured 
a pseudogynic Camponotus mengei from the Baltic amber (viele infra 
p. 139). From analogy with the conditions in Formica , Wasmann 
would probably infer that the presence of pseudogynes in the amber 
Prenolepis and Camponotus is an indication that these ants were in- 
fested with beetle parasites similar in habits to Lomechusa and Ate- 
meies, but Donisthorpe has recently communicated to me reasons for 
suspecting that the presence of pseudogynes even in Formica colonies, 
does not always necessarily imply the presence of these myrmecophiles. 
I have figured (Fig. 57 b) the better preserved pseudogynic P. henschei 
which is in the Klebs Coli. (K 868). It measures only 2 mm and is 
therefore somewhat sm aller than the normal worker, as is apt to be 
the case with Formica pseudogynes, and the curious hunched thorax, 
which is intermediate in structure between that of the worker and 
female, is precisely like that of the Formica pseudogyne. The specimen 
in the Geolog. Inst. Koenigsberg Coli. (B 5202) measures 2,5 mm. It 
is badly decomposed and not visible in profile. The pro- and mesonotum, 
however, as seen from above, are large and convex. 
Mayr did not fail to notice the very close resemblance between 
P. lienschei and the recent P. nitens of Southern Europe. This form 
is now regarded by Emery as being merely a subspecies of the North 
American P. imparis Say, which is, therefore, an ancient circumpolar 
species. Although henschei is smaller than either of these recent 
forms, there is a small variety of imparis (var. minuta Emery) in 
Maryland, which is not larger than the fossil species. It is not im- 
probable, therefore, that henschei is the ancestor of the present imparis . 
This, I may state in passing, is always associated with arboreal Vege- 
tation and, in my experience, specifically with oaktrees, as one may 
easily observe in the pine-barrens of New Jersey and the live-oak 
groves and scrub -oak chaparral of California. It is probable that 
henschei lived in similar association with the oaks whose common 
presence in the amber forests is attested by the number of their 
peculiar stellate hairs scattered through the blocks enclosing the 
insects. 
