Hi Linda,
I believe your third spelling, Chlamys cloacata (Reeve, 1853) is the correct
one. Kind of interesting name. Literally translated it means "resembling a
sewer". However I suspect Reeve may have been engaging in a little
"Anglo-Latin" here, and intended it to mean "resembling a cloak". Which
incidentally, is also what the Greek word Chlamys means - a cloak or cape.
Paul M.