CARDIOCERATID AMMONITES FROM THE MIDDLE OXFORDIAN VERTEBRALE SUBZONE OF NORTH YORKSHIRE AND DORSET

Eight species of Middle Oxfordian ammonite belonging to the genera Car dioceras and Goliathiceras are described. The specimens were collected from beds close to the junction of the Hambleton Oolite and the Middl e Calcareous Grit in Yorkshire, and from the Preston Grit in Dorset. T he two faunas appear to come from the same, contemporaneous horizon wi thin the Vertebrale Subzone. The range in variation of ammonite morpho logy within this narrow time span is discussed. One new species, Cardi oceras (Subvertebriceras) yedmandalensis, is described and figured.