I wasn't aware of "hybrid" as an accepted translation for "hinnus".  The
usual noun for hybrid is hybrida.  It does make sense though, since a mule,
after all, is a hybrid.  If "hinnus" can actually mean "hybrid", that would
be a very logical reason for applying the name Hinnites ("having the
characteristics of a hybrid") to this shell, since Hinnites appears to be a
cross between a pecten and an oyster.

Paul M.