166 



Annals of the Carnegie Museum. 



Table III. 



• Giving Results of Comparison of Values for Each Dimension in 

 Two Environments.* 

 DSD 



(Dextro sinistral diameter, or convexity, divided by length giving 

 degree of inflation.) 

 Greater Value in Upper 



Ohio Drainage. 



A. ferussacianus (4) 



Species with Even No. Cases. 



DVD 

 (Dorsal ventral diameter of value or its "height," divided by length.) 



Greater Value in Upper 

 Ohio Drainage. 



Species with Even No. Cases. 



Greater Value in L. Eiie. 



(Distance posterior to extremity from a line passing through median dorso-ventral 



plane of value.) 



Greater Value in Upper 



* Number of cases in which this occurs is given after name of each species — 2-3 

 etc. means 2 cases out of 3, etc. In species with even number of cases, number is 

 given after each. 



