> The ligaments (small external and larger internal) are posterior to the
> beaks, and the large pallial sinus opens on the same side.

Ligaments are almost always posterior of the beaks if they are
definitely to one side of the beak.  Some ligaments extend to both
sides, and internal ligaments are often nearly central and not much
help (except when they are consistently asymmetrical in a particular
direction).

Many cementing bivalves consistently cement on one side, though not
chamids; cementing on the "wrong" valve has been reported in
plicatulids but I don't know how much further checking has taken
place.

A byssus, being associated with the foot, is anterior (though it is in
the middle in anomiids).


--
Dr. David Campbell
Collections Assistant
The Paleontological Research Institution
1259 Trumansburg Road
Ithaca NY 14850

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------