Fissurella and Drymaeus (Mexico)?

[paul monfils]

Hello Wolf,

Welcome to the list.  I'm sorry it has taken so long to respond to your post.  Your limpet is certainly Fissurella barbadensis.  The green interior (actually alternating green and light bands) is a key characteristic of this species.  The fuzzy stuff covering the exterior is calcareous algae, which frequently grow on these shells. The Drymaeus is more difficult, mainly because I don't know land snails as well as marine shells.  The species you mentioned, D. serperastrum, which I was totally unfamiliar with, doesn't seem to have many references available. I can't find it in any book in my library, and even online information is sparse.  However, from the couple of images I was able to locate, I think your ID is probably correct.