ABITS OF BURROWING CRAYFISHES IN THE UNITED STATES.

On May 13, 1883, I chanced to enter a meadow a few miles above
Washington, on the Virginia side of the Potomac, at the head of a small
stream emptying into the river. It was between two hills, at an
elevation of 100 feet above the Potomac, and about a mile from the
river. Here I saw many clayey mounds covering burrows scattered over the
ground irregularly both upon the banks of the stream and in the adjacent
meadow, even as far as ten yards from the bed of the brook. My curiosity
was aroused, and I explored several of the holes, finding in each a
good-sized crayfish, which Prof. Walter Faxon identified as _Cambarus
diogenes_, Girard _(C. obesus_, Hagen), otherwise known as the burrowing
crayfish. I afterward visited the locality several times, collecting
specimens of the mounds and crayfishes, which are now in the United
States National Museum, and making observations.

At that time of the year the stream was receding, and the meadow was
beginning to dry. At a period not over a month previous, the meadows, at
least as far from the stream as the burrows were found, had been covered
with water. Those burrows near the stream were less than six inches
deep, and there was a gradual increase in depth as the distance from the
stream became greater. Moreover, the holes farthest from the stream were
in nearly every case covered by a mound, while those nearer had either a
very small chimney or none at all, and subsequent visits proved that at
that time of year the mounds were just being constructed, for each time
I revisited the place the mounds were more numerous.

[Illustration: Fig. 1 Section of Crayfish burrow]

The length, width, general direction of the burrows, and number of the
openings were extremely variable, and the same is true of the mounds.
Fig. 1 illustrates a typical burrow shown in section. Here the main
burrow is very nearly perpendicular, there being but one oblique opening
having a very small mound, and the main mound is somewhat wider than
long. Occasionally the burrows are very tortuous, and there are often
two or three extra openings, each sometimes covered by a mound. There is
every conceivable shape and size in the chimneys, ranging from a mere
ridge of mud, evidently the first foundation, to those with a breadth
one-half the height. The typical mound is one which covers the
perpendicular burrow in Fig. 1, its dimensions being six inches broad
and