The topic of chiton "preparation" does indeed come up perenially (or is
that bianually?) on this list.  For small chitons (under 35mm or so),
this is a method which has served me well:

1) When convincing them to let go of their home-rocks, try HARD to not
injure them: injured chitons tend to roll up into little balls and
thereby lose all value to anyone or anything which doesn't intend to eat
them.  A thin but not sharp object is good, but if you can "pop" them
off underwater using only your fingers, they are less likely to be
injured than most other methods.

2) Put them immediately into a small container of water taken from the
place you are collecting.  After a while, most of them will be pressed
flat against the bottom.  If you are in a warm place, a couple of
CAREFUL water changes may be helpful during the process.

3) Pour almost all the water off once things settle down.  Then,
IMMEDIATELY  pack a layer of tissue paper over the little guys and press
down firmly.

4) Pour a mixture of 50/50 glycerin and ethanol or polypropanol (NOT
methanol - it doesn't work very well and has toxic fumes anyway) over
the tissue and put more and more paper into the container until it is
packed firmly to the very top. Do not let up on the pressure, or the
chitons will start to curl.  Use over 90% alcohol: anything less is not
as effective in helping preserve them.

5) Pack the paper, saturated with glycerin/alcohol solution, in the
container so that when the lid is closed tightly, it bulges the top of
the container and maintains the pressure needed to keep the critters
flat while they turn from beasties to flat, flexible, well-preserved
specimens of same.

6) After a couple of weeks,  the critters should be a) flat b) flexible,
and c) well preserved for posterity.

Sometimes you may find chitons which occasionally have a beautiful
blue-green pigment which fades quickly after the animal dies (The genus
Tonicella is the one i have encountered in conjunction with this, but i
believe there are others in Ischochitoniidae which also have similar
pigments)  The only way i've found to preserve this beautiful color is
to empty the water carefully, so flatness is maintained.  Then, quickly
pour liquid nitrogen over it/them, and freeze-dry the colorful little
guys as quickly as possible.   If you don't have access to a lab with
these capabilities, then i suggest you experiment and report the results
back to the list: i'd LOVE to find an easier way, since i no longer have
this sort of access myself!!

 From April truly is the cruelest month New Scotland,
Ross Mayhew.

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