|A 14th century European depiction of a pack horse, from a copy of the Tacuina sanitati, a book on health. From Wikipedia, public domain|
Dorsers are peds or paniers carried on the backs of horses, on which higiers use to ride and carry their commodities. It seems this homely, but most useful instrument, was either first found out, or is the most generally used in this county, where Fish-jobbers bring up their fish in such contrivances, above an hundred miles from Lime to London."
Map - Lyme Regis