Barbatia conundrums:
Abbott & Dance show only velata, Sowerby, (no mention of foliata) and indicate
that decussata, Sowerby and lima, Sowerby are both synonyms.
Oliver shows foliata Forskall and decusatta Sowerby as separate species, and
says that lima Reeve is a form of foliata.
 
I have many subquadrate specimens from Fiji that most closely resemble
lima.... as seen in examples so labelled at NMNH, and look like Oliver’s 2nd
form of foliata   The distinctions made by Oliver between foliata and
decusatta are not constant among these.
 
(Oliver says that foliata’s ribs are narrow, elevated, nodulose....that
decussata’s ribs are wider than the interspaces but not nodulose.  Some of my
specimens represent the opposite ...some with narrow, elevated but not
nodulose ribs, and some with wider ribs that are nodulose. Almost none of
those dead-collected have any periostracum remaining.)
 
So what’s the difference between lima Reeve and Sowerby?  Is velata  a syn. of
foliata?