Hi, Harry and Everyone Else! Well, I found the dratted shell, and I discovered that I have at least one other smaller shell of the same specie. The distinguishing feature is not the yellow on the exterior, but on the inside under the hinge, there is a short yellow streak perpenicular to a line through the hinge; and this streak is bounded on each side with a purplish streak. I should know this specie, but the name temporarily eludes me. Anyone care to help? Cheers, Linda