toward each other. While three or four individuals may sometimes be
trapped at a single mound, more than two are seldom so caught, and most
often only one in one night. Trapping on successive nights at one mound
often yields the larger number, yet in some cases the number is
explained by the fact that two or three nearly mature young are taken,
and the capture of several individuals at a single mound can not be
taken to indicate that all are from the one den. Our investigations tend
strongly to the conclusion that only one adult occupies a mound, except
during the period when the young are in the parental (or maternal) den.
In the gassing and excavating of 25 or more mounds we have never found
more than one animal in a den, except in one instance, and then the two
present were obviously young animals.


SENSE DEVELOPMENTS.

Without making special investigations through a study of behavior or
other special methods, one can speak in only general terms regarding
what appear to be the special sense developments of kangaroo rats. The
eyes are large, as is very often the case in nocturnal animals, and when
brought out into the bright light of day the rats perhaps do not see
well. Yet, if an animal leaves a den which is in process of excavation,
and follows one runway, even in bright sunlight, it makes excellent
speed to the next opening, often a distance of several yards. Whether
this is accomplished chiefly by the aid of sight or in large measure by
a maze-following ability, such as experiments have shown some rodents to
have, can not be stated without precise experimentation. Marked ability
to follow a maze would not be at all surprising in view of the
labyrinthine character of the underground passages which make up the
normal habitation.