Hi Rita, I understand how the Wentletraps get confusing. One thing I can tell you straight away is the Epitonium lamellosum is not found at Sanibel. In my experience, the 5 most common Sanibel wentletraps are: Epitonium angulatum, E. humphreysii, E. tollini, E. rupicola, E. multistriatum matthewsae (roughly in that order- the first two are much more common than the last three). There are others but they are much rarer. Of these five, it is the first 3 that provide the greatest confusion (especially when the shells have become at all worn). If you find the shell is cream colored between the white ribs (costae) it is more likely to be humphreysii. Humphreysii is also typically thicker ribbed than angulatum or tollini. Though humphreysii can have a slight angle to the ribs at each shoulder in a pristine shell, angulatum's "angles" tend to be more pronounced (basically squared rather than rounded). Also an adult angulatum tends to be larger than humphreysii (3/4-1 inch vs. 1/2 to 3/4 inch). Although I have found plenty of Juvenile angulatum and humphreysii to potentially confuse the issue further, it is good to note that juv. angulatum tend to have very extreme squared off shoulders. Tollini, often confused with humphreysii, is usually more slender, has strictly rounded costae, and doesn't get above a 1/2 inch. Rupicola is unmistakable unless eroded to the point of losing all color. Typically the shell has clear brownish bands that set it apart. Multistriatum matthewsae is usually very small (<1/2 inch) and has many ribs per whorl (>15). This sets it apart from all the preceding wentletraps. I hope this information is helpful. -Take care, Kevin