The dictionary describes phrenology as:
    The study of the shape and protuberances of the skull, based on the now discredited belief that they reveal character and mental capacity.

but, this really doesn't do the subject justice. Captain FitzRoy was a strong believer in phrenology; he almost rejected Charles Darwin as his ship's naturalist because of the shape of his head. FitzRoy believed that his three Tierra del Fuegians' head shapes changed after they were "civilised" in England and reverted back to their primitive shape when returned to the wild several years later.

Here are the two best sites that I found on Phrenology:

• The Phrenology Page
• Phrenology Study Guide

    The best way to get a definition for one of the regions is to enter "phrenology" and the word in a Google search.