Dear Conchlers,
Here is a good website to consult for advice on asking copyright holders for
permission to reproduce their work. This is the author's manual for the
Treatise on Invertebrate Paleontology. The sections on copyright are pretty
far into the file:
http://ukanaix.cc.ukans.edu/~paleo/author's_manual.html
My advice is, Don't give up without asking. The copyright owner might say
yes, or might agree to let you reprint an illustration on a one-time basis
if acknowledgment is given. You won't know till you try. It's true that they
are generally more willing to let you use their material if they know it's
not for profit.
Andrew K. Rindsberg
Geological Survey of Alabama