bunhill fields cemetery, city road, london

mid c18 tombstone, its encrustation of coal tar and smog being cleaned away by acids in the rain. below the skulls was an epitaph written on a hanging shroud, but were there once terms on each side, or are they just degraded volutes ? I can't remember ever seeing such figures on a gravestone, though caryatids and herms appear on much earlier and larger jacobean tombs