STATION IN FRESH-WATER MUSSELS. 



295 



2. Lexingtonia dolabelloides conradi (Vanatta). — Dia. less 

 than 50 per cent. 

 Unio maculafus Conrad, '84 (Elk and Flint R., Ala.). — Plenrobema 



maculatmn Simpson, '14, p. '/■^y. 



Dia. (Simpson) : 46 per cent. 

 Pleurohema appressum Simpson, '14, p. 747 (Tuscumbia, Ala.; 



Tennessee and Holston R., Tnnn.). 



Dia. 47 per cent. 



I submit here the following tables : 



Loc. No. Max. Min. Av. 

 Tennessee River. 



Florence 4 71 62 67 dolab. 



Bridgeport S 68 54 60 dolab. 



Ratbburn i 74 74 74 dolab. 



French Broad River, Boyd Creek. 2 61 59 60 dolab. 



Clinch River. 



Solway I 50 50 50 dolab. 



Clinton 4 54 49 52 dolab. (conr.) 



Agee I 50 50 50 dolab. 



Clinch River Station I 44 44 44 conr. 



Clinchport i 42 42 42 conr. 



St. Paul I 45 45 45 conr. 



Cleveland 5 40 39 40 conr. 



Raven 6 39 34 36 conr. 



Richland 2 38 36 37 conr. 



Cedar Bluff 2 37 36 36.5 conr. 



Similar conditions prevail in Pozvell River, where no dolabelloides 

 have been met with, and where the percentage of conradi drops to 

 37 at Big Stone Gap. 



Remarkably enough, I did not find this shell in the Holston 

 proper (a case parallel to that of Fiisconaia edgariana), but it is 

 present again, in the shape of conradi, in North and South Fork 

 Holston, and again the law is evident here. This is shown in the 

 following table. 



Loc. No. 

 South Fork Holston River. 



Bluff City 4 



Emmett i 



Fish Dam i 



Max. Min. 



Av. 



