PLATE XXI. 



Fig. 



la, b, c. Ammonites Lewesiensis ; from the Grey Chalk, near Dover; in the collection 

 of S. J. Mackie, Esq., of Folkstone, p. 46. 



la, side view. 



lb, front view. 



lc, outline of a septum. 



2. Ammonites leptophyllus ; outline of a septum of the specimen, Plate XXII, tig. 1. 



6a, b, c. Ammonites Wiestii; from the Chalk with silicious grains, Chardstock, 

 Somersetshire; in the collection of J. Wiest, Esq., p. 47. 

 6a, side view. 

 6b, back view. 

 6c, section of a whorl. 



