I've been following the discussion on species with interest and amusement.  
Two comments:  Tom E., you dropped a new one on me with the bit about
mating kingsnakes and cornsnakes to get fertile offspring.  I'm tempted to
try it.  Paul M., a philosophical caveat: you say species are "subjective"
and  "exist as electrochemical impulses in our central nervous systems, not
as objective realities in nature."  You are right in the first description
but an electrochemical impulse is just that.  Ideas are not brain impulses,
though surely there are connections and conjunctions between them.      
On another subject, Andrew's comments on Aesop remind me that a colleague 
passed along a marvelously witty column from the Aug. 10, 1998 NEW YORKER 
magazine which uses the common names of shells to move along a zanny
storyline.  Its on the last page, titled "Shore Leave" by Henry Alford.  I
hope I' m not just telling you all about something you read in one of the 
messages I deleted.
Lastly, I'm having trouble interpreting Gary Rosenberg's lists of correct 
names for species.  I've been trying to get my periwinkles straightened out
and thought I was fine until I tried L. planaxis and L. scabra.  The list 
spits out 15 to 20 names none of which seems right.  I thought the first
name was the correct one but that seems wrong for these.  I'd ask Gary
directly but I don't have his email address and this question may be
relevant to other Conchlers.