CHANGES FOR ADAPTATION IN THE MOLE 339 
hairs. In Scapanus the scales of the tail have small tubercles. 
In Talpa the scales do not form distinct rings. 
We thus have in the mole a protective covering well adapted 
to the environment and habits of the animal. The structure 
of the fur is such as to offer the least possible resistance to move- 
ment in any direction. The parts exposed most in the process of 
digging are either covered by scales or coarse hairs, or both, an 
arrangement which is well suited to the use of these parts, ena- 
bling them to be kept more free from dirt. As will be described 
later, some of these hairs are sense organs, and as such can serve 
their function best when they are isolated. 
The fortress of the mole, according to Paycraft (08), follows 
no fixed design, but varies according to conditions. ‘The com- 
plicated galleries are incidental and have no reference to pre- 
meditated escape from danger. He believes the breeding for- 
tress is built by the female and inhabited only by her. The male 
has a somewhat more complicated place of his own. The female 
begins building her fortress in autumn or early winter. The 
young, from two to seven in number, leave the nest in June or 
July at the age of about five weeks. The numerous tunnels at 
the nest are made partly, at least, to provide a place to put the 
dirt excavated in building the nest. The fortress is about 1 
foot high and sometimes 3 feet in diameter. The outer fortress 
incloses a hollow chamber beneath which the nest is located. It 
consists of a ball of grass and leaves about 6 or 7 inches in 
diameter. 
The location of the fortress or nest, according to Wood (’08), 
is under logs, stumps, or deep under the surface. The nest never 
harbors more than one adult mole (Scheffer, 713). The runways 
which extend out in all directions from the nest are used mainly 
as highways to the feeding grounds, which are reached by lateral 
tunnels from the main passages. Le Court (’88) says that these 
main burrows are larger than the others, but are not large enough 
for two moles to pass each other in them. He also says that 
different individuals may use the same passage, but they ‘‘never 
intrude upon each other’s hunting-ground.”’ Wood (’85) claims 
that deeper in the soil there is often a much larger burrow which 
