>Hi, everyone!
>
>I need some help with several conchological
>terms which appear to be used in different
>ways in the literature.
>
>What is a "fossula"?  I had thought it was a
>vertical groove found on the inner lip of
>cypraeids and ovulids.  However, Liltved, in
>"Cowries and Their Relatives of Southern
>Africa", p. 34, refers to the fossula as a
>"columellar depression" and the ridge next to
>it as the fossula.  Which is correct?
>
>Also, the terms "columella" and "base" appear
>to be used in different contexts in various
>publications.  Some glossary definitions are
>not clear.  What is the difference?
>
>I look forward to your assistance.
>
>Conchologically yours,
>Ron Noseworthy

A fossa is a groove, NOT a ridge. A fossula is a small groove.
Fossula I seem to remember being used for the depression produced by
columellar inductural deposits in Cypraea and Trivia (should also be
used for Erato and Willungia) and if present in ovulids too, and also
possibly for the dorsal groove in Trivia?

Columella is the lower (anterior, abapical) part, usually parallel
with the coiling axis, of the labrum (inner lip); the part enclosing
the umbilicus, if present; bounded by the parietal area posteriorly
and the canal if present. In tightly-coiled shells it forms a solid
core, prominent in logitudinally-sectioned shells. In
siphonostomatous forms it forms the inner margin of the canal.

Base is the lower (anterior or abapical) surface of a gastropod
shell, which surrounds the columella; in Calliostoma it's the
flattened bit the shell sits on if sat down upright. In most shells
it's the part of the final whorl abapical of the periphery (widest
part of the shell).

In hyperstrophic shells what appears to be the columella and base are
in fact NOT!

--
Regards
Andrew