night a strange individual was liberated on a mound. It deliberately
entered one of the openings, but after about two minutes' time made an
exceedingly rapid exit, running rapidly out of sight as if pursued,
though the owner of the home did not appear outside of the burrow. There
can be little doubt that the stranger was precipitately ejected by the
owner. We suspect, though this is a point difficult to prove
satisfactorily, that _merriami_ does not always store food supplies for
itself, but visits the burrows of _spectabilis_ regularly to pilfer the
seed stored therein. The observed facts thus far recorded which suggest
this are that in no _merriami_ burrow examined has a store of food been
found, and also that in trapping for _spectabilis_ on its own
characteristic mounds one catches a large percentage of _merriami_.

On two separate occasions Vorhies has observed the smaller species
running over the mounds of the larger, actually carrying away the grain
which had been placed to entice the larger when it might appear. (In
these cases the larger species did not put in an appearance until near
morning.) Furthermore, the dens of _merriami_ are often connected by
distinct runways with those of _spectabilis_, indicating much traveling
or visiting. That this is probably not friendly visiting is suggested by
the certainty with which an individual of the larger species will strike
and kill one of the smaller when they are placed together in the same
inclosure. The word "thief" expresses this suspected relationship better
than would the term "parasite."

It is not to be expected that such obvious shelter retreats as the
mounds of _spectabilis_ should fail to attract the attention of other
animals. We have found a small gecko (_Coleonyx variegatus_), scorpions
of two or three undetermined species, and certain insects (of the Order
Orthoptera) to be very common inhabitants of the dens. With the