The Collaborative International Dictionary of English v.0.48:

Dodman \Dod"man\, n.
   1. A snail; also, a snail shell; a hodmandod. [Obs. or Prov.
      Eng.] --Nares.
      [1913 Webster]

   2. (Zool.) Any shellfish which casts its shell, as a lobster.
      [Prov. Eng.]
      [1913 Webster]