Hi Helmut,
I can send you a Tegula pellisserpentis.  I have several nice large ones.
In addition to "serpens" or "serpentis", anything with the folowing names is
named after snakes:
anguis, anguineus, anguinus
coluber, colubrinus
echis, echidion
natrix, natricis
ophis, ophidion
vipera, viperinus
I don't know how many of these pertain to mollusks.  I can think of a few -
Serpulorbis colubrinus, Siliquaria anguina, Ischnochiton ophioderma,
Nanomelon viperinus - good luck with the display.  Oh - also, the genus
Colubraria!
Regards,
Paul M.
Rhode island