GENERAL DESCRIPTION 



isms which they generate and nurture ; and there are 

 intermittent ebbs and flows in the Great Lakes, after 

 the simiHtude of tides. Many lakes do not diminish 

 by outflow, evaporation, or absorption, in the hottest 

 weather, nor overflow in the wettest seasons, remaining 

 always at a uniform stage. Others suddenly lose half 

 their volume, or drain off altogether. Some swarm 

 with fish at times, and again are apparently barren. 

 All of these phenomena are easily accounted for on 

 the hypothesis of underground connection and in no 

 other way. 



As a matter of fact, there is a far more copious and 

 extensive fluvial system under the earth than there is 

 on top of it, any engorgement thereof forcing the flow 

 to the surface, where it finds vent and manifestation 

 through crater cones, geysers, sink-holes, artesian wells, 

 and intermittent springs ; also throwing out fish, not 

 eyeless cave-dwellers, but wide-awake, lusty and well- 

 formed specimens of whitefish, sunfish, goggle-eyes, 

 mud-cats, blue-cats, suckers, eels, bass, and pike-perch, 

 as well as lizards and sea-shrimps. We do not find 

 trout represented in the list because it is a primitive 

 species, the subterranean streams having accomplished 

 their general distribution ages ago, under the dispensa- 

 tion of the period. Blind fishes are not thrown out, 

 because they are committed to the lock-up for life, 

 segregated in underground pockets which have, per- 

 haps, no available outlets. At all events, the eyeless 

 fishes which we find in the Mammoth Cave of Ken- 



