128 GLEANINGS FROM NATURE. 



no large rooms, few stalactites, and, in general, may 

 be said to be monotonous. The stream on the floor 

 winds from side to side of the eave, thus making the 

 frequent crossing of it necessary. 



In a shallow pool of water, 1,200 feet from the en- 

 trance of the cave, a fine specimen of the blind cray- 

 fish was secured, and about fifty feet distant, in a 

 deeper pool of the main stream, numbers of a com- 

 mon species of an above-ground crayfish, Cambarus 

 bartonii (Fab.), were found. Whether these seeing 

 forms pass their entire lives in the total darkness of 

 the cave or whether they make an occasional visit to 

 the outside is a question as yet unsolved. The same 

 species was found in several other caves and seems to 

 have a liking for clear, cold water and underground 

 resorts. If these habits be continued a " new species" 

 of blind crayfish will, in time, result; for there is lit- 

 tle doubt but that the ordinary eyeless form has 

 evolved from a seeing one which, ages ago, found its 

 way, voluntarily or otherwise, into the under-ground 

 streams. Finding there the struggle for existence less 

 deadly than among its numerous kin of the surface 

 waters it slowly adapted itself to its surroundings. 

 Having no need for its eyes they, in time, became 

 aborted, for nature always rids her objects of every 

 organ which, from a change of environment or habit, 

 becomes to them useless. 



Several specimens of above-ground beetles were 

 taken from the margin of the stream in this cave, but 

 they had probably been washed in by the heavy rains 

 of the week before. The most interesting insect 

 secured was a cave harvestman, Scotolemon flavescens 



