IV. MORPHOLOGICAL FEATURES OF CERTAIN MUSSEL- 

 SHELLS FOUND IN LAKE ERIE, COMPARED WITH 

 THOSE OF THE CORRESPONDING SPECIES 

 FOUND IN THE DRAINAGE OF 

 THE UPPER OHIO.* 



By Norman McDowell Grier. 

 (Plates II-III.) 



Outline of Contents of Paper. 



Page 



I. Acknowledgments 145 



IL Introductory 146 



III. List of Species Discussed 151 



IV. Physical Conditions and Types of Naiad Faunae 151 



V. Method of Measurement 158 



VI. Table showing the Distribution of Shells Measured 159 



\TI. Results: Table showing Maxima, Minima, and Mean for each Dimen- 

 sion in the Two Environments; Table showing Relative Values of 

 each Dimension in the Two Environments; Table showing Actual 



Measurements of the .Shells 164-172 



VIII. Conclusions 164 



IX. Correlations 1 73 



X. Suggestions as to the Causes of Phenomena and as to Possible Sources 



of Error 1 74 



XI. Bibliography I79 



I. Acknowledgments. * 



To Dr. W. J. Holland, Director of the Carnegie Museum, I am 

 indebted for the use of the facilities of that institution in pursuing 

 this research. In other ways also he made possible its completion, as 

 did Dean J. C. Fetterman of the College of Arts of the University of 

 Pittsburgh. Dr. Arnold E. Ortmann, Curator of Invertebrates in 

 the Carnegie Museum, besides suggesting the problem, has with his 



* Submitted to the Graduate School of the University of Pittsburgh as a major 

 thesis in partial fulfillment of the requirements for the degree of Doctor of Phil- 

 osophy, June, 1919. 



145 



ANN. CAR. MUS., XHI, II, Dec. 9, I92O. 



