I notice that superfamily names of pulmonate shells have been written
variously with the "-idea" suffix or with the "-acea" suffix, depending on
source. Superfamily names in Abbott's Seashells Compendium always end in
"-acea,"  though Abbott used the "-idea" ending in his earlier land shell
book. Is there now a preferred ending for specifically the superfamily level
(not suborder)? Or, am I just seeing out-of-date usage in some cases?

-Burton