MUSSELS OF CUMBERLAND EIVER AND TEIBUTAEIES. 



25 



species that were not found in the Cumberland at all, and others 

 that were quite rare. In these respects they resemble those found 

 in Roaring River in Tennessee. 



Laurel Creek, a tributary of Laurel River, was examined below 

 the dam at Corbin, Ky., July 3. The shores were rocky and were 

 heavily wooded mth a deciduous forest, mixed with hemlock and pine, 

 and still supported a remarkably rich and varied flora. The dam 

 cuts off the upper portion of the river, and no mussels were found 

 above it. There was a city dumping ground near at hand and the 

 water was milky in color and covered with a greasy scum. Below 

 the dam the bottom was very irregular and mostly solid rock, full of 

 potholes and patches of sand and destitute of vegetation. 



We had expected to find a rich and varied fauna, something like 

 that of the Rock Castle River, but could discover only five species, 

 and three of these were represented by a single shell each. This river 

 thus has almost identically the same species as the Clear Fork and the 

 Cumberland above the falls. The poverty of species is doubtless due 

 to the smallness of the stream and the general unsuitable conditions. 



There was no dwarfing of the species, but there were several 

 pecuhar modifications in the color of the nacre which were not found 

 in the main river. These suggest that while there is some inter- 

 course with the Cumberland there is very httle interbreeding. 



The Big South Fork flows into the Cumberland at Burnside, Ky. 

 Our party examined it first opposite Parkers Lake, where there is a 

 fish trap and a low dam. The shores there were high Umestone 

 cliffs, the water was very clear, and the bottom was coarse gravel 

 covered with bowlders and great angular fragments of rock, with 

 some sand between them. Dead shells, recently killed by muskrats, 

 were abundant on the rocks and on the dam at the fish trap. Twenty- 

 eight species were obtained here, but although seven or eight of them 

 were good button shells, they were not sufficiently abundant to make 

 the gathering of them profitable. At Sloans Shoals, 6 miles from 

 Burnside, during the autunm of 1910, Mr. Boepple found about 20 

 species, securing them all with a rake. At the riffles, 2 miles above 

 Burnside, the present party found large but rather scattered beds of 

 mussels, by far the greater number of which were noncommercial. 

 There were 32 species in all, and evidently some of them had yielded 

 good returns in pearls, for there were many piles of shells^ along the 

 river bank and the bed had been thoroughly worked over. 



Minute marginal cysts were abundant in the edge of the mantle of 

 Unio gihhosus, often leaving small pits along the margin of the shell. 

 Baroques and the distomid of KeUy were found in Quadrula tuher- 

 culata, and a few large Atax in SympJiynota costata. Several of the 

 U. gihhosus and two of the Pleurohema were gravid. The latter 



