MOUNTAIN ANTS OF NORTH AMERICA. 



463 



lowing table from Gary's "Biological Survey of Colorado" (1911); 



In his "Life Zones and Crop Zones of New Mexico, Bailey (1913) 

 gives the upper boundary of the Upper Sonoran as 5000-7000 or even 

 8000 ft., the boundaries of the Transition as extending from 7000 to 

 8500 ft. on northeastern and 8000 to 9500 on southwestern slopes, 

 of the Canadian as from 8500 to 11,000 and on warm slopes from 9500 

 to 12,000, of the Hudsonian from 11,000 to 12,000 on northeastern and 

 12,000 to 13,000 on southwestern slopes, the Arctic-Alpine on the 

 Sangre de Cristo Range as all above 12,000 ft. on the coldest slopes, 

 and on especially steep slopes as all above 11,500 ft.; on the warmest 

 slopes as all above 13,000 ft. or on very gradual slopes all above 

 12,500 ft. In Arizona the boundaries of the life-zones ascend some- 

 what higher, as indicated by the following altitudes from Merriam's 

 work (1890) on the San Francisco Mountains (southwest slopes): 

 Lower Sonoran 4000-6000 ft.. Upper Sonoran 6000-7000 ft.. Transi- 

 tion 7000-8200 ft., Canadian 8200-9200 ft., Hudsonian 9200-10,500 ft., 

 Arctic-x\lpine 10,500-11,500 ft. In the Chisos, Davis and Guadeloupe 

 Mountains of Western Texas, according to Bailey (1905) the Transi- 

 tion Zone extends from about 6000 ft. on northeast slopes to the top 

 of the ranges (8000-9500 ft.). In Mexico the upper boundary of the 

 Transition must be even higher. North of Colorado the zonal bound- 

 aries descend rapidly till in the latitude of Vancouver and Maine the 

 Canadian zone, which extends across the continent, is at sea-level, 

 so that we find at this level such forms as Camponotus whympcri, modoc, 

 and larvigatus, the two latter of which do not descend below 4000 to 

 6000 ft. in the Sierras, while whyrnperi and laevigatiis are not known 

 from elevations under 7000 to 8000 ft. in Colorado. On the other 



