The first shows the demon of fashion between the horns of a woman's headdress. On either side of her are slanderers with protruding tongues. The second shows a preacher flanked by a pair of ancient Britons. A leaflet suggests that they have 'manes like lions to indicate courage, snouts like pigs to convey ignorance and large ears to show that they listened'. Despite the second image, misericords tend to depict secular rather than religious themes and often show pagan figures like the green man.
A misericord is a shelf on a choir stall seat to support the occupant while standing (according to Simon Jenkins). My lack of Latin meant that I looked up the term in a couple of places. It has several related meanings: (1) an amercement, which is a penalty or fine at the mercy of the inflictor, (2) a thin-bladed dagger used to give the coup-de-grace or mercy stroke, (3) an indulgence granted to a member of a religious order, and (4) compassion, pity. In the case of these shelves the term would more or less mean a 'small mercy'.