four high. Two other forms are shown in Fig. 2. The burrows near the
stream were seldom more than six inches deep, being nearly
perpendicular, with an enlargement at the base, and always with at least
one oblique opening. The mounds were usually of yellow clay, although in
one place the ground was of fine gravel, and there the chimneys were of
the same character. They were always circularly pyramidal in shape, the
hole inside being very smooth, but the outside was formed of irregular
nodules of clay hardened in the sun and lying just as they fell when
dropped from the top of the mound. A small quantity of grass and leaves
was mixed through the mound, but this was apparently accidental.

The size of the burrows varied from half an inch to two inches in
diameter, being smooth for the entire distance, and nearly uniform in
width. Where the burrow was far distant from the stream, the upper part
was hard and dry. In the deeper holes I invariably found several
enlargements at various points in the burrow. Some burrows were three
feet deep, indeed they all go down to water, and, as the water in the
ground lowers, the burrow is undoubtedly projected deeper. The diagonal
openings never at that season of the year have perfect chimneys, and
seldom more than a mere rim. In no case did I find any connection
between two different burrows. In digging after the inhabitants I was
seldom able to secure a specimen from the deeper burrows, for I found
that the animal always retreated to the extreme end, and when it could
go no farther would use its claws in defense. Both males and females
have burrows, but they were never found together, each burrow having but
a single individual. There is seldom more than a pint of water in each
hole, and this is muddy and hardly suitable to sustain life.

[Illustration: Fig. 2 Crayfish Mound]

The neighboring brooks and springs were inhabited by another species of
crayfish, _Cambaras bartonii_, but although especial search was made for
the burrowing species, in no case was a single specimen found outside of
the burrows. _C. bartonii_ was taken both in the swiftly running
portions of the stream and in the shallow side pools, as well as in the
springs at the head of small rivers. It would swim about in all
directions, and was often found under stones and in little holes and
crevices, none of which appeared to have been made for the purpose of
retreat, but were accidental. The crayfishes would leave these