those of _D. ordii_.


RUNWAYS AND TRACKS.

Still other features add to the interest in the dwelling places of
_spectabilis_. Radiating in various directions from some of the openings
of the mounds well-used runways are to be seen, some of them fading out
in the surrounding vegetation, but others extending 30, 40, or even 50
or more yards to neighboring burrows or mounds (Pl. V, Fig. 2; Pl. VI,
Fig. 1). These runways and the entrances to the mounds are well worn,
showing that the inhabitants are at home and are at some time of day
very active. The worn paths become most conspicuous in the autumnal
harvest season, when they stand out in strong contrast to surrounding
grass. One usually finds not far distant from the main habitation one or
more smaller burrows, each with from one to three typical openings,
connected by the trail or runway system with the central den, and these
we have called "subsidiary burrows" (Pl. VI, Fig. 2). These will be
again referred to in discussing the detailed plan of the entire shelter
system.

Examination of the runways and of the denuded area about a mound
discloses an abundance of almost indecipherable tracks. The dust or sand
is ordinarily much too dry and shifting to record clear footprints, and
there are no opportunities to see footprints of this species recorded in
good impressionable soil. Very characteristic traces of kangaroo rats
may be readily observed in the dust about the mounds, however, and these
are long, narrow, sometimes curving, furrows made by the long tails as
the animals whisk about their work or play.