1922 ] 
Ants of the Genus Formica in the Tropics 
175 
Arizona and California. Some of these together with a few 
allied species occur also in Mexico, but apparently only at 
elevations of about 8000 ft., as far south as Hidalgo in the state 
of Guerrero (lat. 18°). In all probability the same Formicas 
inhabit the mountains of the state of Oaxaca and therefore 
extend the range of the genus to the southern limits of the 
Nearctic Realm, that is to the Isthmus of Tehuantepec. 
Although there would seem to have been every opportunity 
both in Asia and Mexico for the spread of the species of Formica 
into the tropics, the only recorded instances of its occurrence 
are the following: 
(1) Bingham in 1903 cites the taking of three workers and 
a female of the common European F. rufibarbis Fabr. by W. 
L. Distant in Pretoria, South Africa, only a short distance from 
the tropic of Capricorn (26° S.). This seems to be the only 
record of the genus occuring in the southern hemisphere. There 
would seem to be little doubt that the species was imported 
directly from Europe. 
(2) According to Emery F. fusca var. qlebaria, a common 
ant in central and southern Europe, has been imported into the 
gardens of Algiers. He calls attention to the fact that this insect 
does not occur in Crete nor on the smaller islands of the Mediter- 
ranean. 
(3) In 1913 Forel described a var. formosae of F. picea 
Nyl. from Taihorin, Formosa, which is on the tropic of Cancer. 
F. picea is a boreal European ant, usually found in peat-bogs. 
ForeFs variety may perhaps occur at a considerable elevation 
in the mountains, which in Formosa rise to an altitude of 9000 
to 14,000 ft. In this case, therefore, we may be dealing with a 
relict instead of a recent importation like the two previous cases. 
Emery believes that the F. fusca var. filchneri described bjr 
Forel from China is really F. picea. 
I was astonished to find among a fine collection of ants made 
for me by Dr. J. W. Chapman at Dumaguete, on the island of 
Negros Oriental, Philippines, several specimens of two species 
of Formica. One of them, represented by a number of workers, 
agrees in all respects with European and North American 
