PLATE XXII. 



Fig. 



la, h. Ammonites leptophyllus ; from the Upper Chalk of Greenhithe, Kent; in the 

 collection of L. Barrett, Esq., reduced to two fifths its natural diameter, 

 p. 48. 

 la, side view. 

 lb, front view. 



2a, b, c. Ammonites Gollevillensis ; from the hard Chalk of Datnlaght, in the county 

 of Deny, Ireland ; in the Museum of Practical Geology ; reduced to 

 three fourths its natural diameter, p. 48. 



2a, side view. 



2b, front view. 



2c, outline of a septum. 



