12 
Psyche 
[March 
the possibility might be considered that the Kota Dah Formica 
sample represents a labelling error, or the misplacement of a vial 
with North American ants in the Fairchild collecting kit. Such 
explanation seems much more likely than any introduction of For- 
mica glacialis live into Sumatra. Other examples of this sort of 
mishap are very common in the Wheeler collection. In papers pub- 
lished in 1922 and 1927, Wheeler reported and discussed a similar 
case for the Philippines. 
With this puzzling case once solved, the natural geographic dis- 
tribution of the genus Formica appears to be entirely holarctic. 
Biogeographic boundaries of course do not follow straight lines; 
rather, they reflect topography and other factors affecting climate. 
Mountain ranges carry holarctic elements southward toward and 
into the tropics in both the Old World and the New. Thus the 
presence of Formica species in the high mountains of Taiwan and 
Burma is not surprising, since these ranges are nearby outliers or 
direct continuations of the holarctic uplands of mainland Asia. 
The range of the genus includes also the high elevations of central 
Mexico, in North America. 
Nevertheless, that Formica could at one time have had a much 
wider or somewhat different distribution can still be supported by 
its richness, greater than previously recognized, in living species in 
the southern half of the Holarctic region, and by the presence of 
fossil Formica among numerous other subtropical and warm tem- 
perate insects found in the Baltic Amber of Oligocene age. 
Acknowledgements 
I am indebted to Mrs. Favreau, American Museum of Natural 
History, New York, H. E. Evans, Museum of Comparative Zool- 
ogy, Harvard University, and D. R. Smith, U.S. National Museum, 
Washington, for loan of specimens. E. O. Wilson and W. L. Brown 
have my thanks for critically revising the manuscript. Research 
supported by National Research Council of Canada Grant A6501. 
References 
Gregg, R. E. 
1969. Geographic distribution of the ant genus Formica (Hymenoptera: For- 
micidae). Proc. Ent. Soc. Washington 71(1): 38-49. 
Wheeler, W. M. 
1922. Ants of the genus Formica in the Tropics. Psyche 29: 174-177. 
