Average sizes holds for only one collection or one group of collections.
 Almost all data taken using the sells in private collections is biased,
either by the area the collection covered, the depth covered, and by the
collector's desires for the colledtion.  Collectors highly favor the
high sizes and don't bother with small shells, and certainly many to
most don't collect shells with defects.  If you based your entire
opinion on such collections, you might come to the conclusion that all
of a species are giants (compared to what?)and never had defects even
though the majority of shells in a species such as conus may have severe
growth lines broken lips.  You might consider that in some species there
is no protoconch as most are broken off.  Schilders wrote about this
subject several times in Hawaiian Shell News.

The Schilders were probably the principal dividers of Genus Cypraea into
many genera based on the radulae.  Most recent scientific people use
those genera.  Others use those genera as subgenera, which makes a lot
more sense for people working with only the shell (Conchologists?).  In
taxonomy, you are free to make your own choice as to whose taxonomy to
accept.  I use Cypraea as a genus to make it clear what group of shells
you are talking about since almost anyone would consider Cypraea a group
in their collection.  Why make life difficult for customs people and
Fish & Wildlife people.  Using the "Schilders" genera as subgenera
serves both purposes as the subgenus can be used or not.
--
                     Aloha from Wesley M. Thorsson
Editor of Internet Hawaiian Shell News, a monthly Internet Publication
           122 Waialeale St, Honolulu, HI  96825-2020,  U.S.A
       http://www.hits.net/~hsn/index.html   or
        http://home.att.net/~w.thorsson/index.html