140 
Psyche 
[December 
correlation between the dying away of colonies of old mounds, 
and the maturity of trees which brings shading and presumably 
difficulties of food getting. The subject of shading as a cause of 
decay is very important and may be the decisive factor in the 
effect of old trees upon ant mounds. 
Although in the Alps the natives may find their way by the 
elongation of the E. W. axis of mounds of Formica exsecta (as 
confirmed by Huber, 100 yrs. ago); — in Timonium, many nests 
seem elongated N. S. with longer south slope, but that this is not 
universal is indicated by the following measurements made for 
me in April 1920 by Mr. Spielman. 
Twenty vigorous nests in the region, on the flats, wer g 
measured as to diameters N. S. and E. W. and as to angles at th 
top of the nest along those directions of compass as follows . 
E. W. angle 
N. S. angle 
Diameter 
Diameter 
Degrees 
■ E. W. 
Inches 
N. S. 
130 
145 
63 
63 
130 
125 
57 
44 
120 
155 
60 
60 
120 
120 
46 
57 
125 
140 
67 
86 
125 
135 
28 
26 
115 
140 
36 
40 
130 
135 
66 
74 
130 
125 
63 
62 
130 
145 
82 
89 
125 
100 
50 
48 
120 
130 
56 
65 
125 
100 
50 
48 
120 
115 
42 
40 
130 
125 
44 
60 
125 
130 
55 
52 
110 
115 
45 
40 
120 
120 
52 
56 
125 
150 
80 
73 
120 
120 
40 
42 
— 
— 
— 

i 2475 
2570 
1082 
1125 
rage 
123.75 
128.5 
54.1 
56.25 
While these 
measurements 
show that 
some 
nests do 
have any extension toward the South, which would lower the 
angle and increase the diameter N. S. as compared with the E. 
W., yet on the average there is a slightly greater angle and greater 
diameter in the N. S. direction. 
