Hellmouth is the entrance to Hell envisaged as the gaping mouth of a huge monster, an image which first appears in Anglo-Saxon art, and then spread all over Europe, remaining very common in depictions of the Last Judgment and Harrowing of Hell until the end of the Middle Ages, and still sometimes used during the Renaissance and after. It enjoyed something of a revival in polemical popular prints after the Protestant Reformation, when figures from the opposite side would be shown disappearing into the mouth. Image taken from page 95 of "Bygone Warwickshire" edited by William Andrews, 1893.