S9S7. 96(79.1) 



Article XIX.— THE ANTS OF THE GRAND CANON. 

 By William Morton Wheeler. 



During the spring of 1905 Dr. B. E. Dahlgren and myself visited 

 several localities in New Mexico and Arizona for the purpose of collect- 

 ing and studying the desert invertebrates and certain plants to 

 be used in the construction of some of the large vertebrate groups 

 in the American Museum of Natural History. While on this expedi- 

 tion we made an excursion to the Grand Cafion and spent three days 

 (May 25 to 27) in a study of its fauna and flora, so far as these were 

 accessible from the Bright Angel Trail. Special attention was given 

 to the Formicidas as a group of insects of more than ordinary interest 

 from the standpoint of geographical distribution. I therefore col- 

 lected all the species I could find from the Kohonino Forest on the 

 rim of the canon down to the bed of the Colorado River, 5000 feet 

 below, noting the altitude and environment of each colony, so far 

 as this was possible in the brief time at my disposal. The first day 

 was spent in the great pine forest on the rim, the second was devoted 

 to the Bright Angel Trail, and the third to the Indian Gardfen and the 

 adjoining Angel Plateau. 



Of the few naturalists who have visited the Grand Canon for the 

 purpose of studying the geographical distribution of its animals and 

 plants, I may mention Merriam and Coville and McDougal. In his 

 valuable paper on the biological survey of the San Francisco 

 Mountains and the adjacent Desert of the Little Colorado^ Merriam in- 

 cludes a brief but excellent account of the vertebrates and more conspic- 

 uous plants, with a list of 21 species of mammals and 57 species of birds 

 taken on the southern wall from the rim to the bottom of the Grand 

 Canon. His conclusions are summed up in the following paragraph : 



"In descending from the plateau level to the bottom of the 

 canon a succession of temperature zones is encountered equi- 

 valent to those stretching from the coniferous forests of northern 

 Canada to the cactus plains of Mexico. ^ They result from the com- 



' Results of a Biolooical Survey of the San Francisco Mountain Region and Desert of the 

 Little Colorado in Arizona. North American Funa. No. 3- U. S. Dept. Agricult.. Divis. Ornith. 

 and Mammal. Washington, 1890. 136 pp., 13 plates and s maps. 



2 "The extremes of temperature are well illustrated by the fact that the lowest t>-mp.'rature 

 of the twenty-four hours at the bottom of the canon was 80° Fahr. at 4 a. M., Sept.-mb»T rj, 

 while at the same time thick ice formed on a bucket of wat<r at the top of the carton. 



329 



il 



G8 



