346 MEMOIRS OF THE CARNEGIE MUSEUM 
cornered, and cannot retreat further. It is then readily secured, but care must be 
taken not to pull it out by the claws, which may be easily broken off, thus damag- 
ing the specimen. The creature should be always seized by the carapace. : 
Sometimes this work is very difficult and tedious, and I have often been com- 
pelled, chiefly in the case of Cambarus carolinus, to dig as deep as three feet before 
succeeding in capturing the crawfish. In order to avoid unnecessary labor as far 
as possible, I select burrows in which the water stands near the surface, refusing 
those which evidently go for a long distance through dry soil. Generally there is 
ample opportunity to choose between the numerous burrows of one and the same 
colony of chimney-builders. Now and then it happens that the work is rendered 
easier by the action of the crawfish itself. It occasionally comes to pass that, after 
haying disturbed the entrance of the hole by digging down far enough to reach the 
water, the crawfish may be seen coming forward, apparently trying to ascertain the 
the cause of the disturbance. This isa good chance to seize it, but one must be 
quick, since it generally is the only chance to get it easily, although I remember 
cases when the crawfish came out again and again, just so far as to be plainly seen, 
but darted back at every attempt to seize it. Males are more frequently caught 
in this way than females, and such captures are made most frequently in cloudy or 
rainy weather. It is very rarely that there is a chance to capture the crawfish at 
the mouth of the undisturbed hole, when it is sitting at or near the top of the 
chimney, or on the ground away from the hole. This happened only once or twice 
in my experience. 
I have tried to discover means of compelling the crawfish to come out of its 
burrow, but without much success. Bisulfide of carbon will not avail since it floats 
upon water. I tried chloroform, which sinks in water, but without success. Only 
once had I the satisfaction of driving a specimen of Cambarus menongalensis out of 
its hole by using unslacked lime. In this case I had dug a hole nearly three feet 
deep without being able to reach the bottom. I happened to have with me, espec- 
ially for this purpose, a small tin box with unslacked lime, and dropped the con- 
tents into the hole, where it apparently sank to the bottom. Within three or four 
minutes the crawfish was discovered hurriedly working its way upward in the hole, 
and was easily taken. This method, however, can be used only in a limited way, 
since the holes generally are not straight enough to afford a chance. to drop the lime 
to the bottom, and, if the lime becomes lodged somewhere above the point where 
the crawfish is staying, it drives it away from the mouth of the hole, and eventually 
kills it before it can be reached. (As to the use of lime for destroying crawfishes, 
see infra, VI, 4.° 
