106 ANIMAL COMPETITORS 
overmultiplication; but the only sort now of 
importance in that direction is the southern 
cotton-rat (genus Sigmodon.) The common 
species (S. hispidum) is typically a denizen of 
the Atlantic coast from North Carolina to 
Florida, but its varieties extend the specific 
range westward to Mexico. The total length 
is 10-1014 inches, two-fifths of which belongs 
to the tail. The color varies a good deal, but 
in general is a yellowish grizzle above, and 
ashy to whitish below. 
Their natural habits much resemble those 
of their neighbors, the pine mice, and like 
them they have not only surface runways but 
long galleries and nesting-places under the soil. 
They may be very numerous without attracting 
much attention because of this cryptic manner 
of life, and still more because they rarely come 
abroad until after dark. There have been 
times, as in 1889 in western-central Texas, 
when they swarmed in a regular ‘‘plague,’’ and 
played havoc with the corn-crop. They are 
especially numerous, always, along the borders 
of cotton-fields, and Bailey records that in 
Texas their runways are often fairly lined with 
