8 MUSSELS OF CUMBERLAND EIVEE AND TKIBUTARIES. 



On the whole, however, the benefits seem greater than the disad- 

 vantages. 



Incidentally it is worthy of note that the water privileges at 

 Cumberland Falls have been leased to a company which has already 

 begun operations toward establishing a power plant for furnishing 

 electricity to Louisville and other cities. 



FAUNISTIC DIVISIONS OF THE RIVER BELOW THE FALLS. 



For our present purpose we may divide the river below the falls 

 into four sections, fairly well separated by natural conditions, and 

 by differences in the relative numbers of the various mussels. These 

 sections will be discussed in order, beginning at the falls and pro- 

 ceeding toward the mouth of the river. 



First section, from Cumberland Falls to Celina, Tenn., 17f} miles. — 

 While there are numerous and rich mussel beds along this portion 

 of the river, there is no commercial clamming. This is chiefly due 

 to the high percentage of culls, small species, and pinks, the latter 

 mostly elephant-ear (Unio crassidens). The most important com- 

 mercial mussel is the southern mucket (Lampsilis ligamentina gihha). 



The elephant-ear is not killed in any great numbers by pearlers 

 because it is not looked upon as a pearl-bearing species, while other 

 mussels, supposed to contain pearls, are often nearly exterminated. 

 Up to the present time, moreover, this mussel has been refused by 

 the buyers for button factories. Consequently it has been neg- 

 lected or culled out by the fishermen in the lower sections of the 

 river and left comparatively free to breed, the glochidia to be picked 

 up by fish and carried up toward the falls. Natural conditions have 

 in some way also given the purple spike ( Unio gihhosus) an advantage 

 over other species above the falls. Similar conditions may have 

 been equally favorable to the closely related elephant-ear below the 

 falls. Perhaps these considerations will help to explain their pre- 

 ponderance in these two localities. 



There are 19 mussel beds in this section of the river and the pro- 

 portion of commercial shells and culls, together with the size of 

 the bed and the kind of bottom, are shown in the following table: 



