James,
 
From an amatuer,
 
holotype - the actual, single specimen the author used to describe the
species.
 
paratype - the other specimens of the species collected originally
collected by the author.
 
syntype - they are all syntypes if the author did not designate a
specific shell as the holotype.
 
lectotype - if a later author selects one of the syntypes to serves as a
holotype.
 
All of this is paraphrased from "The Encyclopedia of Seashells," by Dr.
Gary Rosenberg.  I think it can also be found in his articles on the COA
web page.
 
Tom Eichhorst in New Mexico, USA