MUSSELS OF CUMBERLAND RIVER AND TRIBUTARIES. 33 



brightly rayed that for a time they were regarded by the clammers 

 as possibly a new species. Harpeth River, a tributary from the 

 south which enters the Cumberland a little way above Lock A, was 

 examined 5 miles above its mouth. The bottom here was of shingly 

 gravel, changing to solid rock and farther up to beds of soft mud. 

 There was formerly a large mussel bed here, but the backwater from 

 the lock dam has killed the mussels in the lower portion of the bed. 

 Another large bed was reported miles farther up the river. 



The unusual size and thickness of the shells obtained here suggest 

 that this river would yield exceptionally good button material. The 

 margins of the shells were much pitted, indicating parasites in unusual 

 abundance. The presence of fine large L. ventricosa and S. costata 

 so near the mouth of the river is remarkable, since both of these 

 species are absent from the Cumberland. 



Below Lock A we saw numerous sites of old shell piles where clam- 

 ming operations had been carried on in the past. At Half Pone Bar 

 the current was swift, the water shallow and somewhat turbid, and 

 the bottom firm gravel and sand. The large number of specimens 

 and species is at least partly due to the peculiar configuration of the 

 bottom and the low stage of the water, the conditions being similar 

 to those at Salt Lick Island (see p. 29). The great majority of the 

 shells obtained were young, but many of them were eroded at the 

 umbones. P. donaciformis was exceptional in being very thin and 

 having a pink nacre. The large number of Plagiola is noteworthy, 

 together with the only specimen of Truncilla jiorentina found below 

 Nashville. 



At the Seven Mile Ferry above Clarksville the current was rather 

 feeble, the water clear, and from 5 to 8 feet deep, and the bottom 

 composed of fine gravel. From this point on down the river a crow- 

 foot bar was employed, similar to that used by commercial clammers 

 but shorter and smaller, and furnished with 50 hooks. The latter 

 were of two kinds, the ordinary form used by clammers and an 

 improved form invented by Mr. Boepple, having a knob at the tips 

 to prevent small mussels from taking hold or larger ones from dropping 

 off. Hauls were made 200 feet long, the first as near the shore as 

 possible, and each succeeding one 10 feet farther out. The detailed 

 record of the different hauls made at a few stations is given in full, 

 in order to convey a more accurate idea of the number and distribu- 

 tion of the mussels, and the ease or difficulty with which they could be 

 caught. Such a record was kept for all the stations in this portion 

 of the river, and forms an important factor in determining the relative 

 abundance of the mussels. 



At Owl Hollow Bar, 2^ miles above Clarksville, we found a swift 

 current with clear water over a clay bottom, more or less mixed with 

 gravel. This bed had been worked for eight years and showed signs 



