PECULIAR HABITS OF THE CRAY-FISH. 785 



localities, and found the prairie completely covered with them for 

 acres. The majority were along the sides of a sluggish brook that 

 held water scarcely an inch deep, and from here they extended away 

 up the slope, so that the most distant heaps were perhaps two hun- 

 dred feet away from the stream ; and, in some cases observed in other 

 localities, no stream or brook could be found, a low, damp spot being 

 the center from which the mounds seemed to radiate or branch. So 

 vast were the numbers of heaps that I could walk for a long distance 

 by merely stepping from one to another, and not unfrequently they 

 were in such close proximity that walking was difficult : a horse in 

 passing over the field presented a curious appearance, evidently find- 

 ing it hard work ; and a carriage would have been wrenched to pieces 

 or badly strained in a short time. The makers of these mounds or 

 heaps were discovered by digging, and proved to be a genus of the 

 common fresh-water cray-fish ; and, though I was familiar with their 

 mound-building habits, their location so far from streams was entirely 

 new, and shows that the little creatures are better adapted to a semi- 

 amphibious life than many of their allies that are considered true water- 

 livers. 



In making inquiries and investigations into their habits, I found 

 that they differed from our species of the East in certainly, at times, 

 not requiring water. In other words, they passed a certain portion of 

 the time out of the water, and occasionally they would retreat from it ; 

 and when floods came they would leave what would be naturally con- 

 sidered their native element entirely and take to dry land. 



In a small river that flows through the prairie north of Freeport, 

 Illinois, I found great numbers of cray-fish close in shore, nearly every 

 stone concealing one or more that were well protected by their almost 

 exact resemblance to the bottom in color. Four or five feet above the 

 level of the water were numerous heaps formed in the black clay mud, 

 and almost every one of these contained a cray-fish that was living in 

 water that must have come from above, as the holes had no connection 

 with the river below. Generally I found the little animal out of water, 

 just within the hole, and upon being alarmed it would drop down. In- 

 vestigation with a stick would show that there were several inches of 

 muddy water in the bottom. The inmates, having no loop-hole for 

 escape, were quite savage, biting at the intruding stick with their 

 powerful claws, and allowing themselves to be almost lifted from the 

 mound. 



It would seem strange to find these animals living in this condition 

 if there were not some rational explanation, and it is evident that too 

 much water is equally as disagreeable to the cray-fish here as, if not more 

 so than, not enough, and the mounds and heaps above and away from 

 the streams are in this locality the results of the animals' attempts to 

 obtain a location where they can remain in the water or out in safety. 

 To crawl out upon the open bank of a brook would expose them to 



VOL. XXIX. 50 



