250 THE AMERICAN MIDLAND NATURALIST 



Lampsilis luleola rosacea, Dekay. Lampsilis liiteola, Lamarck. 



Lampsilis_ ovata canadensis, Lea. Lampsilis ovata ventricosa, Lamarck. 



The accompanying map, and list of localities as given in Plate 

 III showing collecting stations will give some idea of their distribution 

 in the Upper Ohio Drainage and L. Erie. The material used was 

 collected by Dr. A. E. Ortmann over a number of years, (1903-07), 

 in Western Pennsylvania and L. Erie, or secured by him in smaller 

 amount as exchanges. Dr. Ortmann, besides suggesting the value 

 of aij introductory study to the color problem in Najades, has done 

 everything in his power to assist the investigation, for which 

 data was obtained at the Carnegie Aiuseum in Pittsburgh. I am 

 indebted to Dr. W. J. Holland, Director, for the freest use of the 

 Museum's facilities in connection. 



III. — Physical Conditions and type of Mussel Fauna. 



The type of Mussel Fauna has already been admirably treated 

 in papers by Walker -(18) and Ortmann, (10-13 inclus.). These 

 and the physical conditions concerned have already been sum- 

 marized by the writer elsewhere (i); those for L- Erie being ably 

 stated by Jennings, (&), and for the Upper Ohio Drainage in the 

 Water Supply Papers of the U. S. Geological Survey.* At this 

 point we may conveniently add Simpson's observations on the 

 type of Mussel Fauna concerned particularly with regard to the 

 problem we are dealing with. (16). "Species from the Mississippi 

 Valley are more richly colored internally and externally than those 

 of any other part of the globe. . . . All the Mississippi Valley 

 species of Najades that have entered the St. Lawrence or any 

 part of the Atlantic Drainage area have become changed . . . the 

 nacre losing its briUiancy; instead of the bright epidermis often 

 painted beautifully with rays in wonderful patterns, rich greens, 

 yellows, olives we have mostly dull, livid, ashy, rusty reddish 

 or brownish exteriors." Simpson did not believe these changes 

 were due in any measure to climate or colder water, for the shells 

 reach a similar development elsewhere. He further remarks that 

 the changes in form, size and coloring have led students to create 

 new species and varieties for what were originally Mississippi 

 Valley shells. For sake of convenience however, the outstanding 



* See Horton, T. H., Hall, M. R., Bolster, R. H. Leighton, M. D. "Surface 

 Water Supply of the United States 1907-08. Part III Ohio River Basin, 

 P- 29, 35, 47. Water Supply papers, U. S. G. S. 



