1927] The Occurrence of Formica fusca L. in Sumatra 41 
hind tibia stouter, less reclinate and more conspicuous. Pubes- 
cence much as in the true fusca , but finer and somewhat more 
dilute on the upper surface of the gaster, but distinctly longer on 
its sides and venter. The gaster is somewhat more shining and 
metallic, more as in the North American var. subcenescens 
Emery. The color is a deeper black than in fusca and the legs 
and palpi are more blackish, the mandibles and antennae some- 
what deeper red. One of the specimens has distinct bluish 
reflections like the Mexican F. subcyanea Wheeler. The male 
and female, when discovered, will probably exhibit additional 
differences. 
We must, I believe, regard the var. fairchildi as a true 
tropical relict and not as a recent importation. Its occurrence 
in a remote locality, at a considerable altitude and among pines 
makes the latter supposition very improbable. It is quite dif- 
ferent from the var. japonica Motschulsky from Japan and 
China, a form which we might, perhaps, expect to find in Indo- 
nesia. The present wide distribution of fusca and its many 
varieties throughout northern North America and Eurasia, and 
its very close relationship, if not identity, with F. flori Mayr of 
the Baltic Amber (Lower Oligocene Tertiary) suggest an even 
wider distribution during the geologic past. Further investi- 
gations at high altitudes in Sumatra and possibly also in Java 
and Borneo may show that fusca has survived also in other 
localities in these tropical islands. A somewhat similar case is 
presented by F. picea Nylander, a peat-bog ant which is widely 
distributed over northern Eurasia and as far south as Switzerland 
and Thibet, though it is not known to occur in North America 
or Japan. In 1913 Forel described from Taihorin, on the island 
of Formosa, a variety of this ant ( formosce ) which like the above 
described fairchildi would seem to, be a tropical relict. 
