134 Scientific Intelligence. 
leading from the water, along the sands and up into the neighboring 
low lands. Visiting these paths early in the morning, while yet the 
fogs were unrisen, | often found the Aséacus returning from his mead- 
ow rambles, but never could ascertain the precise object of these ram- 
bles, whether predatory or otherwise. 
viding the waters of the Chicago River and the Aux Plaines, is a wet 
marsh, lying near the deposit of bituminous limestone. ‘The marsh, at 
paths of the Astacus, some of them showing evidences of a very re- 
ly he was lost. By careful examination in the rank herbage, I found 
he had disappeared in a well or cistern about 10 or 12 inches deep and 
13 wide. Here was his own pool, provided for by himself, for the long 
summer draughts. In following up other trails I invariably found them 
terminating in similar pools. In many the inmate was present, whilst 
absent in others.” 
Extract from a second letter from Dr. Stevens, dated Nov. 23.— 
“ Our friends, the Astaci, increase in interest as I become more and 
Hate ae 
ing much damage to dams and embankments. On the little Genesee, 
they have within a few years compelled the owners ofa dam to rebuild 
it. e¢ former dam was built after the manner of dykes, i.e. with 
upright posts, supporting sleepers laid inclining at an angle of 45° up 
On th ere laid pl 
els of dirt and gravel in the course of a night. I have seen this sea- 
son, where they had attempted the present dam, piles of dirt, of at least 
one bushel. 
They now travel over the dam in their migration, often climbing up- 
right posts two or three feet high, to gain the pond above.” 
It is to be regretted that no specimens were procured in order to as- 
certain to which species the above Crawfishes belong : ther 
Cambarus fossor, or C. diogenes, or some other. This deficiency, 
mud chimneys being 
built upon the exterior surface of the wells, such as are constructed by 
C. diogenes in the district of Columbia. s Barnp. 
* 
