340 Annals Entomological Society of America {Vol. VIII, 
none of the ants of the temperate zones, with the exception of 
a species of Forelius (chalybeus Forel) in Argentina and a species 
of Pheidole (Ph. metallescens Emery) in the Gulf States. Nor 
does metallescence occur in the ants of the tropics outside of 
Australia, if we except a few species of Diacamma, Leptogenys 
and Polyrhachis in the Indomalayan region, a few species of 
Monomorium and Formica in Mexico and several species of the 
genus Macromischa which has its center of distribution in the 
Antilles. 
3. A third progressive line of development has led to 
certain large-eyed tropical ants, in which there is a contrast of 
black, yellow or red in bands, spots or larger areas involving 
certain segments or regions of the body. This diversification 
of color is often secured or enhanced by the development of 
areas of dense white or golden pubescence or pile, especially 
on the gaster. The tints are more vivid than in the ants of 
the first and most primitive category, and seem to indicate that 
their large-eyed possessors have some slight appreciation of 
color for its own sake, Hke the butterflies and many flower- 
frequenting flies and beetles. These ants live in open forests 
and are often very-quick in their movements. They comprise 
such genera as Pseudomyrma in the New World tropics, Opis- 
thopsis and Podomyrma in Australia and New Guinea and the 
“bull-dog’’ ants (Myrmecia) of Australia, Tasmania and New 
Caledonia. We may also include in this category many 
tropical species of Camponotus, Polyrhachis and Dolichoderus. 
Not only is the coloration of ants thus influenced or deter- 
mined by light, Keat and aridity, but a peculiar adaptation in 
the investment, or pilosity and pubescence is observed in many 
species which are subjected to the extremes of these conditions 
in desert regions. Thus the species of Deromyrma (cockerelli 
André and albosetosus Mayr), of Pogonomyrmex, Messor and 
Myrmecocystus, the dominant forms in the deserts of our 
Southwestern States, are covered with silvery white hairs or 
pubescence or with both, and in the Sahara similar conditions 
prevail in Cataglyphis (formerly Myrmecocystus) and Messor. 
Cataglyphis bombycina, the most extreme of these forms in 
the development of pubescence, when running over the desert 
sands in the bright sun-light is said to resemble a drop of 
quicksilver. Obviously the brilliant white hairs serve to 
