382 bulletin: museum of comparative zoology. 



species pratensis. In order to simplify the treatment of the forms in 

 the fusca group I have proceeded in a simihir manner to raise cinerea 

 and rufibarbis to specific rank. The constant presence of erect hairs 

 on the gula in the former and tlie pecuharities of nidification and of 

 temperament in the latter, and the complete absence or extreme rarity 

 of transitions between these forms and fusca certainly justify this pro- 

 cedure. 



Among the Nearctic and Palaearctic Camponotinae the only genera 

 at all closely related to Formica are Polyergus, Lasius, M^Tmecocy- 

 stus, and Cataglyphis. The parasitic genus Polyergus is now gener- 

 ally believed to have been directly derived from Formica. This may 

 be admitted without accepting Wasmann's more specific assertion 

 that it has arisen from F. san guinea, since there is no morphological 

 basis for this statement but merely the inference that the slave-making 

 habits of Polyergus are in a more advanced or specialized stage of 

 phylogenetic development than those of sanguinea. It is, of course, 

 possible that the slave-making habits have been developed independ- 

 ently in the two genera. Lasius has been quite distinct from Formica 

 since Eocene or even Mesozoic times, since we find in the Baltic am- 

 ber, which is attributed to the Lower Oligocene, a typical Lasius (L. 

 schiefferdeckeri Mayr), scarcely distinguishable from small varieties of 

 the existing L. niger L., and a species of Formica {F.flori Mayr) per- 

 haps identical with the living F. fusca. The relations of the genera 

 Myrmecocystus and Cataglyphis have been recently considered by 

 Emery. ^ The Old World species of Cataglyphis were supposed to be 

 congeneric with the American species of Myrmecocystus till a few years 

 ago, when I showed that the New and Old World forms must be at 

 least subgenerically distinct owing to the differences in the males and 

 in the arrangement of the ammochaetae in the workers and females.^ 

 More recently Emery and Forel have separated them generically, and 

 the former author concludes that the New World Myrmecocystus arose 

 from the genus Lasius, whereas the Old World Cataglyphis was derived 

 from Proformica. If we accept this conclusion Myrmecocystus and 

 Cataglyphis are heterophyletic genera and their similarity is due either 

 to their having arisen from allied genera or to their having converged 

 through adaptation to life in dry, hot deserts. 



There has been some discussion between Wasmann and Emery 

 concerning the phylogeny of the species representing various groups 



1 Der W^anderzug etc. Loc. cit., p. 102. 



2 Honey-ants, with a revision of the American Myrmecocysti. Bull. Amer. mus. 

 nat. hist., 1908, 24, p. 345. 



