Actually, printing pictures of gastropods with the aperture on top would
be consistent with the way we image most other animals that are normally
presented in dorsal view.  Protozoans, annelids, insects, crustaceans,
arachnids, echinoderms, etc. are almost always illustrated with the
anterior end upward. Likewise, dorsal views of vertebrates - rays and
skates, amphibians, reptiles, birds, bats, etc - are almost always
"heads up". Interestingly, chitons are usually pictured with the
anterior end up as well. Cephalopods frequently appear either way, and
tusk shells are presented in lateral view, sometimes with the anterior
end up, sometimes down. Nudibranch and land slug pictures (at least
drawings) are normally heads-up. But gastropod shells alone have the
distinction of nearly always being printed "upside down", or more
accurately, "front end down", standing on their heads . . . unless the
snail is shown protruding from the shell, in which case they are often
oriented heads-up!

Paul M.