302 CALIFORNIA ACADEMY OF SCIENCES  [Proc. 47H SER. 
Europe. Hence the only forms really endemic and character- 
istic of Cocos Island are the two species of Camponotus. 
The ants, therefore show the same relation as the diurnal 
Lepidoptera to the Galapagos fauna of which Williams says’: 
“Only two species of butterflies were taken on Cocos Island, and 
neither of them occurs in the Galapagos.” It is evident that the 
Cocos ants are decidedly tropical whereas those of the Gala- 
pagos are mainly such as belong to subtropical or temperate 
regions or at any rate to the cooler or subalpine regions in the 
New World tropics. Williams calls attention to this difference 
in the climates of the two island regions. It comes out strongly 
also in the Cocos plants which have been recently studied by 
Stewart.° This author records 77 species of vascular plants 
from Cocos Island, 20 of which are ferns. There are only eight 
endemic species, one of which is a Cecropia (C. pittiert). Thus 
only 8.69 percent of the plants are endemic, whereas the per- 
centage of endemicity in the Galapagos is 40.9. There are, 
however, 27 species common to the two regions, although 11 
of them are ferns. Botanists have repeatedly called attention to 
the great difference between the Cocos and Galapagos plants, 
but this would be expected as a result of the pronounced climatic 
differences. The data derived from a study of the ants are too 
meager to enable me either to accept or to reject Stewart’s view 
that Cocos is a true oceanic island of more recent origin than 
the Galapagos and that it has received its biota as “flotsam and 
jetsam”’ from the Central American mainland. | 
Family FORMICIDZ# 
Subfamily PONERIN A 
1. Euponera (Trachymesopus) stigma (Fabricius) 
Formica stigma Fabricius, System. Piez. 1804, p. 400 3. 
Ponera quadridentata Roger, Berl. Ent. Zeitschr. 4, 1860, p. 
285 9: 
5 Williams, F. X. The Butterflies and Hawk-Moths of the Galapagos Islands, 
Expedition of the California Academy of Sciences to the Galapagos Islands, 1905- 
1906, III. Proc. Cala. Acad. Sci. (4) 1, 1911, pp. 289-322, 2 pls. 
§ Stewart, A. Notes on the Botany of Cocos Island. Expedition of the California 
Academy of Sciences to the Galapagos Islands, 1905-1906, V. Proc. Calif. Acad. Sci. 
(4) 1, 1912, pp. 375-383. 
