26 MEMOIRS NATIONAL ACADEMY OF SCIENCES. [vol.xii. 



Lot 143. Bridgeport, Ala. Dead shells from old Indian camp above the town near the 

 Widows Bar. November 1, 1901. Stevenson sheet. About 50 shells of turrita, including 

 some very large individuals. 



Lot 146. Bellefonte, Ala. Dead shells from old Indian camps at head of Bellefonte Island, 

 at mouth of Mud Creek, November 10, 1901. Three shells of turrita. 



Lot 187. Bellefonte, Ala. Dead shells from old Indian camps just above Sublet Ferry 

 (west bank). November 10, 1901. Over 25 specimens of turrita. 



Lot 148. South of Dodsonville, Ala. Two or three miles above Pine Island. Dead shells of 

 turrita from a shell heap or Indian camp, in McCamy's field. November 11, 1901. There was 

 quite a little shoal water in the region. This is about 15 miles above GimtersviUe, which is 292 

 miles from the headwaters and 105 miles from Chattanooga, and forms the extreme southern 

 limit. This was the downstream Umit for the genus lo in my collecting. The shells appeared 

 to be more scarce in this region than they were at Bellefonte and Bridgeport. Scottsboro sheet. 



Below Cowley Landing search was made in the region of Guntersville, Ala. (Gadsden sheet) . 

 About 2 miles above the mouth of Town Creek were large shell heaps, at an old Indian camp. 

 This and two other small sites were carefully examined but no lo were found. A similar search 

 was made at Manchester and Fort Deposit below Guntersville where there were large shell 

 mounds, particularly at Manchester. In all, about half a dozen of these heaps were examined, 

 and although they contain many other molluscan shells, the desired kind was lacking. 



Farther downstream at Hobbs Island, near Whitesburg, Ala., an intelligent fisherman did 

 not know lo. At Whitesburg there is a very large shell heap on the river bank. This is sectioned 

 and exposed by the cutting of the river so that it could be seen to extend along the bank for 

 about one-fourth of a mile, and had a height of from 1 to 2 feet. This immense shell heap was 

 composed largely of Unionid shells. The undercutting had strewn shells along the river margin 

 in large numbers. Even with these exceptional opportunities for examination no lo were found. 



In the vicinity of the Muscle Shoals, above Florence, Ala., there is a vast area of what 

 appears to be a favorable habitat for lo. The river here spreads out over an extensive rock 

 bottom. This region was examined (November 4, 1901) and large shell heaps were found. 

 At the Elk River Shoals, near Miltons Bluff (354 miles from the headwaters), one heap was 

 found at the south bank, about one-fourth of a mile upstream from the bluff. Here Unionids, 

 Strepomatids, and Viviparids were present in immense quantities. On the following day a large 

 shell heap, "Penniewinkle Mound," was examined. This is on the north bank of the river 

 near the head of the canal. This remarkable heap is about 300 feet long, and about 25 feet high, 

 and is composed largely of Viviparid shells. If lo was present in this part of the stream, it seems 

 that such a collection could hardly be made without accidentally including some specimens of 

 lo. Furthermore, local fishermen, familiar with Viviparids, did not know lo. 



It may appear that the search of the lower part of the river below Guntersville was unneces- 

 sary, but it seemed the safest course to follow, particularly as there appeared to be a possibility 

 of an isolated colony on the Muscle Shoals. The apparent absence of these shells in the lower 

 reaches of the river examined seem to indicate that the shells are not indefinitely roUed or washed 

 downstream but tend to be relatively local ; an inference further supported by other data. It is 

 probable that the shells become eroded and corroded at a rate which prevents their extensive 

 downstream transference through the long reaches of eddy water. 



Since my examination of the Tennessee River, through the kindness of the veteran col- 

 lector, Mr. A. A. Hinkley, of Dubois, 111., I have examined the lo shell which he collected on 

 November 10, 1904. It was collected by him alive, and the remains of the dried animal and 

 the operculum now remain with the shell. Mr. Hinkley 's label is as follows: "/o spinosa Lea. 

 Tennessee River at the foot of Muscle Shoals, south shore, with Angitrema and Anculosa, which 

 were very numerous. This specimen was the only lo found." The apical portion of the shell 

 is badly eroded, so that the character of the apical whorls is unknown, but I am inclined to 

 consider this turrita. 



This shell forms the extreme downstream known hmit of lo, and at the same time its 

 extreme western limit. 



