414 MKMOIKS OF THE CARNEGIE MUSEUM 



down to a depth of a foot or even more. These burrows are found along tlie banks 

 of the streams, and the opening is often not in the water, but away from it, but 

 rarely more tliau a lew feet. The deej^est l;)uri-ows ai'e found in late summer and 

 fall, when tlie small streams are almost or entirel}^ dry. Then necessity compels 

 the ci'awfish to dig deep to ivaeh the underground water. 1 have observed burrows 

 eighteen inches deep in a vertical direction (see Plate XTJ, Fig. 1). Under these 

 conditions a consideralile 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," whicli may be fully equal in .size to those 

 of the typical chinuiey-builders. Here we see the origin of this habit. ('. hartoni 

 is not an haVjitual chimney-builder, 1)ut 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 nmd-piles 

 are the natiu-al consequences of the attempt of the crawfish to accommodate itself to 

 these peculiar conditions. 



The manner in which the l)urro\vs 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. hartoni. 



The roughness of a stream presents no obstacle to the presence of '"'. hartoni. 

 Indeed, it prefers small streams which descend in cascades and fall from the hillsides, 

 provided the rocks lying in them are stati(jnary enough. It goes to tlie \ery ui)i)er- 

 most springs and is frecjuently found there associated with C. 'luononijuleuais or C. 

 caroUnus, and also may be found near (J. (Iio(ifii('.-<. 1 have observed cases where C. 

 harto7ii occupied holes, which were apparently built l)y .specimens of these other 

 species, and am able to give the following instances. Digging for C. tnonoiKjiiUvxis 

 at West Brownsville, Washington ( ountv, I found in a large and wide hole a female 

 (J. hartoni (with eggs). The individual was much too small for this hole. To all 

 appearances an old (abandoned?) hole of '''. inonungalensis was here occu]iied by 

 ('. txvrtoni. Similar observations were made at Avonmore Station, Armstrong 

 ( 'ounty, where in the swampy ground of the valley of Long Kun a colony of ('. d'axj- 

 enes was found, and several ('. (liof/fvcs were taken. In two holes, however, a half- 

 grown specimen of C harloni was fovmd, and again these holes were nuich too large 

 for them. This place was about fifteen yai-ds distant from the stream in which C. 

 hartoni was abundant. Another similar case was observed at Creekside, Indiana 

 ( 'ounty. 



(jioing down stream (*. hartoni remains abundant, as long as the character of the 



