Clark and Gillette — Unionida of Little Arkansas River. 65 



gravel being in nearly every case in the center of the stream, 

 and the black muck along the shores and in all the eddies. 



About 100 shells were collected. While the shells were not 

 especially abundant, excellent examples of some of the good 

 commercial species are present; among them the heelsplitter 

 (Symphynota com/plancda) , buckhorn or pistolgrip (Tritogonia 

 tubercuiata) , j'ellow sandshell (Lampsilis anodontoides) and 

 mapleleaf (Quadrula lachrymosa). 



Many of the specimens, especially of the lighter-shelled species 

 such as the floater (Anodonta grandis) and heelsplitter, were 

 obtained in the eddies and protected places in the stream where 

 there was very little current. The heavier-shelled species, such 

 as the buckhorn, yellow sandshell and mapleleaf were found 

 both in the eddies and protected places, and in some instances 

 in the swiftly running stream, but no shells of any kind were 

 found where there was any shifting sand. A favorite place for 

 the heavy-shelled varieties was the lower edges of the sand or 

 gravel bars, while on the tops of these bars where the water was 

 swifter, none was found. We were unable to determine to what 

 extent they were found in similar situations in the deepest 

 water, as we had no tongs or grappling hooks. 



So far as we could learn no mussels were being taken from 

 the river for commercial purposes, although we heard of a party 

 who had obtained quite a valuable collection of pearls from 

 mussels taken in the river. In many of the specimens taken, 

 small poorly developed pearls were found, but not of sufficient 

 size and quality to be of much value. 



Observations were also made on the Big Arkansas above 

 Wichita on August 26. The river at this point is wide and shal- 

 low, the water at this time covering only about one-fourth of the 

 bed. The main channel of the stream did not follow the center 

 of the bed, but crossed diagonally from one side to the other. 

 The current was swift and carried with it a large amount of 

 shifting white sand which gave the water a yellowish creamy 

 appearance. About 3 miles were covered during these observa- 

 tions. Owing to so much shifting fine sand and the changing 

 of the main channel of the river during high water, it is impos- 

 sible for mollusks requiring the support of a permanent bottom 

 to exist in this river at the place of observation. In this three- 

 mile course only one valve of a mussel shell was found and this 



