142 
Psyche 
[December 
State, is in no part sufficiently extensive to be marked by 
entirely characteristic mammals, birds, or plants. In its 
narrow strips along the Missouri Valley below Bismarck, 
down the Missouri and Yellowstone Valleys to Williston, 
along the Little Missouri Valley above the Killdeer Moun- 
tains, and on many dry, warm slopes between these 
Text figure 1. Thoracic profiles of (A) Pogonomyrmex occidenlalis 
(Cresson) and (B) Veromessor lobngnathus (Andrews), both x8.8. 
areas, it is strongly characterized. So near the edge of a 
zone, however, the slight inclination of a slope to the 
north reduces the heat received from the sun’s rays suf- 
ficiently to change the flora and fauna in part or wholly 
to that of the colder, higher zone, while a steep slope fac- 
ing the direct rays of the sun will attract many species 
of the warmer, lower zone above their normal limits.” 3 
The Larva 
Genus VEROMESSOR Forel 
Body curved ventrally, thorax only moderately stout. 
Body hairs sparse and short; of three types: (1) the 
shortest and most numerous, tip simple or bifid; (2) longer, 
3 Bailey, Vernon. 1926. A biological survey of North Dakota. U.S. 
Dept. Agric., Bureau of Biol. Survey. North American Fauna, No. 49. p. 8. 
