I've been organizing a collection of several hundred California Acmaea
specimens. No matter what criteria I glean from the literature for
diffentiating species, I always seem to find many intergrades. This is
particularly true for pelta, persona, and digitalis. Am I not
discriminating well enough, or do limpet species interbreed extensively?
I would appreciate any opinion on this, before I start cleaving nature
wherever I fancy there's a joint.
        Thanks, Bill
 p.s. Someone mentioned wanting to collect shell dreams. I've often had
the classic one - finding an abundance of huge, clean, beautiful shells
in shallow water - but the other week I had a quite different nocturnal
bonanza. Several packages of fabulous specimens arrived at my house and
I gleefully unwrapped them, slowly realizing that I couldn't possibly
afford to pay for them all, and wondering  what spasm of delirium had
led me to order so much. At least I woke up before I had to catalog
them.