Linda,

I believe the common consensus is that the piscivorous (fish eating) cones
are the dangerous ones to man.  I have seen a deadly seven list as well as a
deadly five list.  From Halstead, Bruce W., 1959.  Dangerous Marine Animals,
comes the following (p. 39):

C. aulicus
C. geographicus
C. marmoreus
C. striatus
C. textile (molluscivorous - has to be an exception to every rule)
C. tulipa

I guess this is a deadly six list.  The problem is a lot of the evidence is
anecdotal.  For a better read on venomous cones and their effetc on man read
Dr Harry Lee's three part series on the Jacksonville Shell Club Web page.
Part three of the series deals with cones:
http://www.jaxshells.org/mollusk3.htm

Good luck,

Tom Eichhorst in New Mexico (USA)