Kevin:
 
John was primarily talking about observing the exterior characteristics
of the mollusc animal rather than the disection of the animal to
determine sexual, digestive and nerve systems.  In most gastropods, the
animal exterior characteristics are characteristic of groups of molluscs
within a genus,  and in some cases can distinguish one species.
 
I agree with John that, when possible, all characteristics of a mollusc
should be included when describing a mollusc.  For gastropods, this
includes the animal exterior characteristics plus perculum
and periostracum.  For the same reason, the radula and DNA analalysis
should be described, or at least mentioned as not observed.  These
latter requirements eliminate a good number of shell collectors who
would be doing the science a better service by working with one or more
people who are capable of observing all characteristics.
 
It seems to me that taxonomy has been taking definite steps in this
direction.  The new species descriptions I have been seeing are a lot
more inclusive than those of some years ago.  A number of views of a
mollusc and a more thorough description as well as range of variation is
more common now.
 
Aloha,
Wes