ORTMANN: THE CKAWFISHES OF THE STATE OF PENNSYLVANIA 413 



conditions. In the niountain streauiis tlie rocks are rolled over very frequently, not 

 only at high stages of water, but also under ordinary conditions, and this api)arently 

 does not suit the tastes of this species, and may be even directly dangerous. Since 

 the general direction of the inigratiou of this species in western Pennsylvania was 

 and is up.streain, it is evident that falls and rapids in the mountain regions present 

 effective barriers, In tlie ponds and lakes of western Pennsylvania, connected with 

 the Ohio drainage, this species is very abundant, but here also it always selects 

 stones under which to hide. 



Cdmbarus propinqinis is restricted to Lake Erie and the lake drainage. It lives 

 ill the tributaries of the lake, exactly under the same conditions as C. obscnru.i. In 

 the lake itself it has been found on two occasions. I'r. 1 >. A. Atkinson collected a 

 minil)er at Presque Isle in the l)ay, but particulars as to their habitat were not 

 recorded. The only other specimen from the lake was collected l)y myself on the 

 sandy and gravelly beach near Miles Grove, thrown out by the surf, but alive. It 

 does not seem to be very abundant in the lake, or at any rate seems to favor 

 only certain places, and we may presume that places with stones and rocks on 

 the beach and not too much exposed to the surf are the projjer localities in which 

 to look for it. 



Camhariis fropmqmi s sauhorni in ( Hiioand West Virginia is found under exactly 

 the same ecological conditions as its representative forms in Pennsylvania. 



Nothing was known hitherto as to the ecological habits of C. obscurus and p''"- 

 jnnqmti), except the short notice of Hay (1896, p. 498), that in Indiana C i>ioiiin- 

 quus lives " in the smaller streams hiding under stones, concealed in short burrows 

 along the banks, or resting quietly on the bottom." 



2. The Mountain Sfrram Species: CamlxirKS hartoui. 

 Conspicuously diifering from •the River Species," Camhaniis harhii I favors the 

 rough streams of the mountains, hills, and the u[)lands generally, an<l is absent from 

 the large rivers. The size of tlie .stream may vary. In fact it goes up to the very 

 sources and is found in the s|)rings. The amount of water ma}' be very small. In- 

 deed it is frequently found in streams which dry out superficially during the hot 

 season. But in such cases water is always present at a certain depth. The varying 

 and often scanty supply of water forces this species to accommodate it-self to these 

 conditions, and thus it has Ijecome to a certain extent a burrowing species. It 

 always selects stones to hide under, an<l in larger streams with a permanent .supply 

 of water is satisfied to scoop out a liollow under th.e stone after the fashion of ' '. 

 obscarus. i>ut very often the burrows are more complex, consisting of a hole going 



