414 MEMOIRS OF THE CARNEGIE MUSEUM 
down to a depth of a foot or even more. These burrows are found along the banks 
of the streams, and the opening is often not in the water, but away from it, but 
rarely more than a few feet. ‘The deepest burrows are found in late summer and 
fall, when the small streams are almost or entirely dry. Then necessity compels 
the crawfish to dig deep to reach the underground water. I have observed burrows 
eighteen inches deep in a vertical direction (see Plate XLI, Fig. 1). Under these 
conditions a considerable amount of dirt (mud, sand, gravel), is removed from the 
hole, and this is piled up in more or less regular mounds at the entrance of the hole, 
often assuming the shape of ‘‘chimneys,’ which may be fully equal in size to those 
of the typical chimney-builders. Here we see the origin of this habit. C. bartoni 
is not an habitual chimney-builder, but is content to hide under stones and to scoop 
out shallow holes when the stream has plenty of water. But when the supply of 
water becomes scant it has to dig down to reach it, and the burrows and mud-piles 
are the natural consequences of the attempt of the crawfish to accommodate itself to 
these peculiar conditions. 
The manner in which the burrows are constructed, and the “ purpose” of the 
chimneys will be discussed below when we come to consider the true burrowing 
species, and it may be remarked here, that everything said with reference to the 
latter holds good also for C. barton. 
The roughness of a stream presents no obstacle to the presence of C. bartoni. 
Indeed, it prefers small streams which descend in cascades and fall from the hillsides, 
provided the rocks lying in them are stationary enough. It goes to the very upper- 
most springs and is frequently found there associated with C. monongalensis or C. 
carolinus, and also may be found near C. diogenes. I have observed cases where C. 
bartoni occupied holes, which were apparently built by specimens of these other 
species, and am able to give the following instances. Digging for C. monongalensis 
at West Brownsville, Washington County, I found ina large and wide hole a female 
C. bartomi (with eggs). The individual was much too small for this hole. To all 
appearances an old (abandoned?) hole of C. monongalensis was here occupied by 
C. barton. Similar observations were made at Avonmore Station, Armstrong 
County, where in the swampy ground of the valley of Long Runa colony of C. diog- 
enes was found, and several C. diegenes were taken. In two holes, however, a half- 
grown specimen of C. bartoni was found, and again these holes were much too large 
for them. This place was about fifteen yards distant from the stream in which C 
hartoni was abundant. Another similar case was observed at Creekside, Indiana 
County. 
Going down stream C. bartoni remains abundant, as long as the character of the 
