Kim,
  It appears that Tom Waller had also compared many specimens in coming to
his conclusion that they were the same.  It would be interesting to
perform a multi-variate analysis to see if there is a true conchylogical
difference between these forms.  Would you have data such as height to
width ratios, rib numbers, height to width of the resilial insertion, etc,
etc.?  If you did I know someone who might be able to perform such an
analysis.  Let me know if you have such data, I unfortunately have had the
opportunity of only studying a handful of these "two" taxa.
 
Charlie
******************************************************************************
Charlie Sturm, Jr
Research Associate - Section of Invertebrate Zoology
                     Carnegie Museum of Natural History
Assistant Professor - Family Medicine
 
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