179 



back, with the simpler character of its lobes, and the great size of its 

 saddles, serve to distinguish it from A . Birchii. 



Locality and Stratigraphical Position. — The finest specimens of this 

 shell are found near Charmouth and Lyme Regis, in the zone of 

 A. ohtusus^ associated with A. Brookii on the same slab, and with the 

 large Saurians, Ichtliyosawrus platyodon and Ichthyosaurus intermedium. 

 It is rare m. Gloucestershire, although I have several specimens which 

 which were collected from the railway cutting near Bredon; one of these 

 specimens shewed the arrangement of the septa figured at fig 3 a. 



(To be continued.) 



M 2 



