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 similar manner to raise cunerea 
and rufibarbis to specific rank. ‘The constant presence of erect hairs 
on the gula in the former and the peculiarities 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, Myrmecocy- 
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. sanguinea, 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. flort 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 Wanderzug etc. Loc. cit., p. 102. 
2 Honey-ants, with a revision of the American Myrmecocysti. Bull. Amer. mus. 
nat. hist., 1908, 24, p. 345. 
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