18 MEMOIRS NATIONAL ACADEMY OF SCIENCES. [volxii. 



Group 10. Lot 17. About 4 miles above Kyle Ford, above Sneedville, Tenn. August 

 15, 1899. 



This lot came from a very limited area, a rocky bar across the river, and in the relatively 

 shallow and moderately swift water. These shells were very abundant. About 20 miles down- 

 stream from Clinchport. They are the form hrevis. 



Supl. lot 196. Four dead shells taken from a sandbar below the milldam, near Kyle Ford, 

 Tenn. These are of the same character as lot 17. 



Group 11. Lot 18. Between Kyle Ford P. O. and Sneedville, Tenn., extending over about 

 12 miles of the river. August 16, 1899. Jonesville sheet. 



Lot 21. Upper part of Thirtymile Shoals, between Cloud Ford (southwest of Xenophon, 

 Morristown sheet) and the mouth of Big Sycamore Creek, Tenn. August 18, 1899. 



Swpl. lot 24. Also from the Thirtymile Shoals, which end at about Sheltons Ford. August, 

 1899. Maynardville sheet. 



Lot 20. Needhams Ford, Little Barren, Tenn. August 19, 1899. Maynardville sheet. 



Lot 32. Agec to Offut, Tenn. August 25, 1899. The Powell River unites with the CUnch 

 at Agec, about 89 miles above the mouth of the Clinch. 



Lot 34. Offut to Clinton, Tenn. August, 1899. Covering about 10 miles of the river. 

 Four shells only. 



Supl. lot 216. Clinton, Tenn. August, 1899. Three very spinose shells. 



Supl. lot 188. Hickory Creek Shoals, Knox County, Tenn., north of Loudon. Collected in 

 spring of 1904 by W. L. Julian. Loudon sheet. These are fragments of three dead shells, 

 much worn and evidently derived from farther upstream. About 29 miles above the mouth 

 of the river at Kingston and 30 miles below Clinton. 



Supl. lot 154- Two spinose fragments of dead shells were taken in the CUnch at Kurry's 

 Island north of Loudon, Tenn., in October, 1901, by W. L. Julian. This is the downstream 

 limit observed for these shells in this river. 



Distance from Artrip, Va., the upper limit of lo in the Clinch to the mouth at Kingston, 

 about 290 miles. 



3. HOLSTON RIVER DRAINAGE SYSTEM, 

 a. North Fork of Holston. 



Group 12. Lot 79. Saltville, Va. From. above the ''alkali works" upstream for 2 or 3 

 miles. August 20, 1900. Abingdon sheet. 



This is probably the type locality for lo jluvialis Say. The shells of lot 79 were collected 

 most abundantly from large flat rocks in moderately swift water, which was generally less than 

 knee-deep. Many large bowlders occurred in the river at this place. The river was examined 

 for several miles farther upstream, but no more shells were found. As far as my observations 

 go this lot represents the headwater limits of these shells. It is probable, however, that the 

 upper limit reaches a few miles farther upstream. 



At and below the alkali works the refuse flowing into the river has covered all the rocks 

 and the bed of the stream with a whitish coating. Natives reported that fish had been killed 

 in great quantities by this refuse. Had this factory been located a few miles farther upstream, 

 lo would have become extinct in all this portion of the stream. Such influences show the im- 

 portance of studpng the animals of our streams before such pollution. 



At about 25 miles below this factory, at Holston, Va. (Bristol sheet), the North Fork was 

 again examined on August 13, 1901. Below the mill, the river apparently afforded an excel- 

 lent habitat for lo. The water was shallow, about a foot deep, with an abundance of large 

 rocks covered with a slimy algal growth, and varied in current from eddy to that of moderate 

 swiftness. The water was clear, and yet no shells were found. I then examined the river for 

 about a mile upstream, above the ford. Here favorable looking situations were found on the 

 flat and angular rocky bed of the stream, and farther upstream a fine shoal was found. Al- 

 though the water was very clear, so that the bottom could be very carefully examined, no lo 

 were found, except an old weathered shell. I was told by a resident that occasionally the "alkali" 

 refuse came down in such a quantity as to give the river a milky color. In this we probably 



