318 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
elsewhere. The section did not pass through the main shaft or tunnel 
that connected the ant hill with the subterranean excavations, but a 
little to one side of it. The upper layer of the earth, to a depth of 
half a meter, was undisturbed; then there was one tunnel with a flat 
floor, about 20 to 25 centimeters across, and having a low arched 
roof; below this, at a distance of about 25 centimeters, were two 
tunnels at the same level and of about the same size and shape; 
below these, at a further depth of about 25 centimeters, were three 
similar openings. ‘This arrangement continued to a depth of nearly 
2 meters, the tunnels being more numerous always at the lower 
levels. The tunnels at the lowest level did not form a complete 
row, but the work seemed to have been commenced at the outside. 
This same arrangement of the tunnels has been seen frequently in 
railway cuts and ditches, but nowhere else have I seen so many levels 
or such a clearly defined plan in the placing of the excavations. 
In some other cases noted the number of tunnels connecting the 
above-ground mounds with the Se galleries seemed to vary 
Fic. 4.—Nest of leaf-cutting ant. 
After Belt. ‘*The Naturalist in Nicaragua,’’ p. 80. 
with the size of the mounds—that is, the more ground the mound 
covered, the more passageways there seemed to be to connect with the 
galleries beneath. 
The section through the burrows given by Belt is reproduced in 
figure 4. This section, however, is diagrammatic, and does not claim 
to show the great extent of the galleries. Belt tells, however, of 
galleries 1.5 meters in depth (p. 76). The best evidence I have 
been able to gather in regard to the depth to which the ants penetrate 
has been obtained in cuts along railways and canals, and in deep 
ditches often dug to serve as fences. On Rio do Peixe, near Serro, 
in the State of Minas Geraes, I found the galleries as deep as 2.5 meters 
at several places along a canal under construction. Most of them, 
however, were only about 1.5 meters below the surface at the deepest 
points exposed. At Bomfim, on the Bahia and Sao Francisco 
Railway, I found the burrows exposed in a deep ditch at a depth of 
2.1 meters. 
