20 
William Morton Wheeler. 
itself, like that so frequently seen in several recent genera, and I there- 
fore concluded that this differentiation must have occurred since the 
Lower Oiigocene. I now see that this statement was not only pre- 
mature but erroneous. While it is undoubtedly true that most of the 
species have only monomorphic workers, and while the workers of 
Camponotus mengei are not distinctly differentiated into major and minor 
phases as in most of the living species of the genus, but correspond 
to what are designated as intermediates or medise, I have recently 
discovered unmistakable major and minor workers in Pseudolasius 
boreus and Dimorphomyrmex theryi , as will be seen from the description 
of these ants in the body of this work. It is evident therefore that 
even this peculiar specialization had been attained by certain ants of 
the Baltic amber, although it still remains true that no species has 
been discovered which has pronounced soldier and worker forms like 
the modern species of Pheidole, Oligomyrmex, Pheidologeton etc. The 
minute size of the worker of Erebomyrma antiqua, as compared with 
the male and female, however, would indicate, if Emery’s view is 
correct 1 ), that a soldier form must not only have existed, but have 
already disappeared in the ancestor of this species before the days of 
amber formation. 
The di- or polymorphic differentiation of the worker is not, 
however, the only intraphasic specialization in which the amber ants 
had anticipated their modern congeners. I have also detected the 
existence of ergatoid and pseudogynic females and ergatomorphic 
males, all peculiar specializations of the male and fertile female phases, 
which we should be inclined to regard as of much more recent origin 
than the polymorphism of the worker. The only known females of 
Bradoponera meieri (XXB 1933) and Platythyrea primceva (K 5122) 
are of the ergatoid, or apterous type and resemble the females of 
some recent species of Anochetus and Odontomachus. Emery has figured 
and described a pseudogynic Camponotus mengei 1 ), and I have seen 
two pseudogynes of Prenolepis henschei (Fig. 57). Among thousands 
of specimens of the closely allied Xorth American P. imparis Say, to 
which the European P. nitens Mayr is now attached as a subspecies, 
I have found only a single pseudogyne. This, however, closely re- 
sembles the two amber specimens. But more unexpected than these 
ergatoid and pseudogynic females in the amber is the male of Irido- 
1 ) Die Entstehung und Ausbildung des Arbeiterstandes bei den Ameisen, ßiol. 
Centralbl. XIY, 1894, pp. 53—59. 
9 Deux Fourmis de l’Ambre, etc. loco citato p. 189 Fig. 2. 
