One additional note, lest I create a false impression. The ratio of spire height to overall length as a species characteristic, to help differentiate one species from another, may be useful, when expressed as a species-wide normal average range (which is really the only way a species characteristic can be mathematically expressed), provided the mathematical distributions of the two species do not overlap substantially. However, it is probably not as useful as the spire to body whorl ratio, when used to look at variation within a species or within a population, for the reasons mentioned in my previous post. Ciao Paul M.