Aydin (and others), Thanks for pointing that error out. I inadvertently swapped the teeth for standard deviations and was too intent on the graphic, letting the arithmetic go begging. It may be a relief for you (and others) to know that I don't schedule train traffic! Yet, I do have to work for a living and that has delayed this reply. Now, here is that graphic made better by your math reminder: Labial teeth of Cypraea helvola hawaiiensis (2,600+ shells) -------------------Standard Deviation----------------- __-4 -3 -2 -1 M +1 +2 +3 +4 ---^----^----^----^----^----^----^----^----^-- 10^ 11^12^ 13^ 14^ 15^ 16^ 17^ 18^ 19^20^ 21^ ----------Number of Labial Teeth---------------------- I am partly aware that some non-continuous (meristic) variable are quasi-normally distributed but others are truly Gaussian. I suspect that the labial teeth are in this latter catagory, but research continues. Some thought has been given to a paper but a few facts are only that. Thanks and Aloha. Bob Dayle (a.k.a. makuabob) _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.