1932 ] 
Distribution of Formica ulkei 
129 
area (.sometimes double that of the north slope) than the 
shorter, steeper north slope. Among the 435 mounds tabu- 
lated, sixteen are dead or inactive colonies. In these cases 
the mounds possess a weather-beaten appearance. The sur- 
face layer is not so evident, and vegetation has begun to 
invade the soil of the mound. 
In the enumeration and mapping of the mounds it was 
observed that their distribution in the area is definitely 
Fig. 1, Sample of typical distribution of Formica 
ulkei mound nests. Small, medium, and large mounds 
are indicated by the size of the black dots. The forested 
area is ruled with parallel lines. Clearings are shown by 
the circles around the dots in the interior of the forest. 
Scale is Vz inch = 25 yards. 
limited. The majority, 48.7%, are located along the margin 
of the forest where it is traversed by open lanes or where 
it adjoins open meadow to the east, north, west, and south- 
west. This number includes mounds of all sizes, classified 
as small, medium, and large, although the two latter classes 
predominate. A small percentage, 17%, nearly all of the 
small type, are located in the open, i. e. 10 to 40 yards from 
the forest margin. The remainder, 34.3%, invariably oc- 
cur in small open clearings in the interior of the forest. 
As in the case of the marginal nests the medium and large 
sizes predominate. The following table gives the complete 
