1926] Sequential Distribution of Formica exsectoides Foret 141 
Moreover the angles, running from 100 to 155 degrees, are 
much more uniform in the E. W. than in the N. S. directions; 
thus there are no very flat nor steep angles E. W. while the ex- 
tremes are all found in the N. S. direction. 
When the above anigles are plotted on curves of frequency 
it is seen that the E. W. angles cluster close to the 120-130 
degree norm, in a steep curve, while the N. S. angles spread 
widely right and left from an irregular flat curve having the same 
norm. 
Apparently there is some factor in the N. S. direction acting 
to disturb the conical symmetry the materials of the nest would 
exhibit if deposited without preference, like the sand in an hour 
glass. 
A second set of measurements of vigorous growing mounds 
taken at random in the same general region rather newly oc- 
cupied, was made in October 1920 by students, Spielman and 
Lord, with the results given in the following table : 
Height 
in 
Angle at top. 
Angle of slope to horizon. 
Distance 
over top. 
inches. 
E. W. 
N. S. 
W. 
E. 
N. 
S. 
in inches 
E.W. N. S. 
22 
104 
110 
34 
42 
27 
43 
80 92.5 
11 
121 
102 
28 
31 
55 
23 
42 39.5 
21 
121 
123 
30 
29 
31 
26 
91 90 
7 
131 
130 
26 
23 
22 
28 
31 28 
12.5 
126 
124 
30 
24 
37 
19 
46 53 
11 
112 
115 
34 
34 
3/3 
32 
40 43 
11.75 
108 
126 
30 
42 
24 
30 
43.5 50 
15 
114 
126 
30 
42 
24 
30 
43 . 5 50 
24 
120 
125 
30 
30 
30 
25 
84 : 87 
32 
100 
110 
50 
30 
50 
20 
77 80 
16 
110 
125 
30 
40 
25 
30 
54 55 
24 
120 
125 
30 
30 
30 
30 
90 89 
20 
130 
125 
30 
20 
25 
30 
89 85 
16 
110 
105 
30 
40 
45 
40 
54 54 
14 
120 
125 
30 
30 
25 
30 
58 55 
m 258 
1747 
1796 
482 
487 
483 
436 
923 951 
r er. 
17 
116.5 
119.7 
32 
32.5 
32 
29 
61.5 63.5 
From this table may be gathered that the average angle at 
the top was slightly larger in the N. S. than in the E. W. direction 
and that the distances over the top were somewhat greater, in 
