412 - MEMOIRS OF THE CARNEGIE MUSEUM 
makes holes in the banks of streams. Faxon (1885a, p. 89) reports that Mr. Uhler 
found this species near Cumberland, Md., in “holes in the bottom and sides of a 
canal,” but whether these were made by the crawfish, or were cracks and joints 
between stones, remains doubtful. In the lowlands in Maryland this species, 
according to the same authority, is found under stones in rivers and creeks. We 
may say of C. limosus that it is of all the species of this state the one which most 
decidedly prefers the quieter water of large rivers, canals, and ponds; that it 
likes to hide under stones, but is not at all averse to muddy bottoms and masses of 
vegetation. 
The latter trait distinguishes it from the species of the western rivers, Cambarus 
obscurus, Which dislikes muddy bottoms (without stones) and vegetation. In fact, 
this is so general a rule, that it is vain to look for C. obsewrus in any part of a river 
which has no stones. Only in rare and exceptional cases have I found it not hiding 
under stones, apparently being forced to do so by necessity. I observed this in two 
cases: in the Allegheny River at Larabee, McKean County, and the Shenango 
River at Linesville, Crawford County. In both cases the river runs through peaty 
soil (through the Pymatuning Swamp at Linesville), and it was only after a long 
search that the species was discovered, when I struck places where stones were lying 
in the water. Butit was interesting to note that at both places the supply of stones 
was apparently not sufficient to accommodate all the specimens, and so a number 
of them had to be content with a shelter afforded by the peaty banks, where they 
had built short, horizontal holes, not more than a few inches long, close to the edge 
of the water. These holes are apparently only temporary, and are often abandoned 
and changed, since a number of them were seen on the banks above the present 
water level, which were built and inhabited at a previous higher stage of the river. 
C. obscurus does not love vegetation. The patches of Dianthera americana, so fre- 
quent in our rivers, do not harbour many crawfishes, although they are not entirely 
absent from them; but they do not hide under these plants and their roots, but 
under stones. They always scoop out a hollow under the stone selected, and bring 
out the mud and grayel, throwing up a small rubbish pile in front of the hole, 
which, however, is soon obliterated by the current. The crawfishes are easily found 
by noting these rubbish piles. They rarely go into deep water (possibly only in 
winter), but always are close to the banks in shallow water; but on the other hand 
they never go out of water. In the mountains of western Pennsylvania this species 
is generally absent, and it is apparently the roughness of the streams which causes 
its disappearance. he stones, under which it hides, must be rather permanent in 
their position, and must rest upon a bed of mud, sand, or gravel, to afford congenial 
