116 GLEANINGS FEOM NATURE. 



gether they produce a roaring sound which is echoed 

 far along the main passage-way. 



From this point onward the walls are dripping 

 more or less and are fringed with small stalactites. 

 About 900 feet from the entrance are two large sta- 

 lagmites, one of which, named by Collett " The Image 

 of the Manitou," has been broken. Originally it 

 must have been six feet in height and eighteen inches 

 in diameter. 



In a pool of the stream in the main passage were 

 secured two of the small aquatic insects known as 

 "water boatmen." They belong to the order Hemip- 

 tera, and to the genus Corisa, and were the only "true 

 bugs" taken in Indiana caves. They were probably 

 accidental visitors, since their compound eyes were 

 fairly well developed. 



In the same pool were numerous specimens of the 

 blind crayfish, Cambarus pellucidus (Tellkarnpf). This 

 curious crustacean was found in a number of other In- 

 diana caves, and probably.inhabits every one in which 

 there is a permanent water supply. Careful exami- 

 nation of cave bed streams ought, 



f, e also, to show its occasional occurrence 



Crayfish. ; 



outside of its subterranean homes. 

 During heavy rain-falls the water rushes with great 

 violence through the caves and doubtless often car- 

 ries the crayfish out to the rivers. Here its light 

 color, soft shell and defenseless condition would prove 

 such a heavy handicap that in the struggle for exist- 

 ence its life would be of very short duration. It is 

 usually found in shallow pools with muddy bottom 

 rather than in rapidly flowing water. It moves 



