420, MEMOIRS] OF THE CARNEGIE MUSEUM 
I have repeatedly observed the digging and the removal of the dirt out of the 
burrow. Of course it is impossible to see the digging going on in the field inside of 
the burrow, and consequently this was observed in the laboratory in the case of speci- 
mens of C. diogenes and monongalensis kept in captivity in large glass jars partly filled 
with clay and water. It is not difficult at all to see them at work, and after they have 
been brought into the laboratory the specimens begin to work within a short time, 
digging out the mud, carrying it upward and plastering it all over the walls of the 
jar. After some time (days or weeks), their activity lessens, and not much digging 
is done, producing the impression that they have become discouraged in the effort 
to construct something similar to the burrows in the field. 
In digging the chele of the first pereiopods are used. The fingers are slightly 
spread out, so that they are about parallel, thus acting as forks for digging. They 
are pushed vertically down into the mud on both sides at the same time, and a 
lump of mud is thus loosened and lifted upward toward the ventral face of the 
body. In lifting the chelipeds are bent toward the body (the region of the mouth), 
and finally the ball of mud is appressed to the anterior part of the body and held 
in position by the chele. Very likely also the third maxillipeds take hold of it, 
but it was impossible to ascertain this. In this position, as Goodman expresses it, 
carrying an “armful” of dirt (or rather two armfuls), the crawfish walks slowly and 
deliberately to the mouth of the hole. I have repeatedly observed it coming out in 
nature.” It advances to the top of the chimney and deposits the mud pellet upon 
the rim, finally pushing it into the proper position with the upper (outer) surface 
of the claws. This latter act apparently was seen by Mr. J. DeB. Abbott; but 
according to my experience the mud is not brought up upon the back of the claw, 
but held, as described above, between the folded claws and the anterior part of 
the body. 
After having been disturbed in the field, the crawfishes often begin to work again 
within a short time, and it is chiefly on such occasions that I have seem them at 
work, with the exception of one case, when I saw a large male of C. diogenes at work 
on the evening of April 30, 1905, (Sunday), in Nine-Mile Run, Pittsburgh. The 
the ‘“‘ lateral tail-fins and telson”’ in any way, as suspected by Shufeldt (1896), in the sealing up of the orifice of the 
burrow, is hardly possible. ; 
%' The following particular instances may be mentioned: OC. bartoni ina spring near Burgettstown, Washington 
County, Aug. 4, 1904; C. carolinus at Indian Creek, Fayette County, July 11, 1904; at Ohiopyle, Fayette County, 
July 12, 1904 ; at Myersdale, Somerset County, August 11, 1904 ; CO. monongalensis in Ferp Hollow, Pittsburgh, May 6, 
1904; at Edgewood Park, Allegheny County, May 9 and 21, 1904; April 21, 1905 ; Monaca, Beaver County, June 30, 
1904; at Cheat Haven, Fayette County, September 6, 1904 ; at Cameron, Marshall County, W. Va., May 1, 1905; at 
Morgantown, W. V., May 16, 1905; C. diogenes at Dunbar, Fayette County, September 7, 1904; in Nine-Mile Run, 
Pittsburgh, April 30, 1905. 
