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 mediae, I have recently 

 discovered unmistakable major and minor workers in Pseudolasius 

 horeus and DimorpJwmyrtnex 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^), 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 PlatytJiyrea lyriynmva (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 Camporiotiis mengei^), and I have seen 

 two pseudogynes of Prenolepis hejiscJiei (Fig. 57). Among thousands 

 of specimens of the closely alJied North American P. imparls 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- 



^) Die Entstehung und Ausbildung des Arbeiterstandes bei den Ameisen. Biol. 

 Centralbl. XIV, 1894, pp. 53—59. 



^) Deux Fourmis de I'Ambre, etc. loco citato p. 189 Fig. 2. 



