Article: Lower Kimeridgian ammonites from the drift of Lincolnshire

A collection of ammonites is described from the drift of Lincolnshire; they are of Lower Kimeridgian age, Mutabilis Zone. Almost all of the specimens belong to the genera Rasenia and Aulacostephanus, and include several new species which are grouped into two new subgenera of Aulacostephanus: Xenostephanus and Xenostephanoides. These new forms have only recently been found in situ in England, and are known from the Kimeridge Clay of both east and west Scotland.