PLATE XVIII. 



1. Ammonites NAvicuLARis ; from the Grey Chalk of White Nore, Dorsetshire; in the 



collection of E. H. Bunbury, Esq., p. 39. 



2. Ammonites navicularis ; from the Grey Chalk near Lewes ; in the collection of 



Henry Catt, Esq., p. 39. ' 



3« and b. Ammonites navicularis ; from the Lower Chalk of Chardstock; in the collec- 

 tion of John Morris, Esq., p. 39. 

 3«, front view. 

 3i, side view. 



|a»\1ei1ice.ros couloai/ \a and h. Ammonite s Mantelli ; from the Grey Chalk of Boncburch, Isle of Wight ; in 



the collection of S. Saxby, jun., Esq., p. 40. 

 ^a, side view. 

 45, front view. 



J-, A. iV''--'>'*'Vo.sv».': ' 5^^ jj^ and c. Ammonites navicularis; from the Lower Chalk of Chardstock; in the 



collection of John Morris, Esq., p. 39. 

 5«, side view. 

 5(5, front view. 

 ^ Qe^f^'W ^^' f^'o^^ vi^^ ®^ t^^ inner whorl of the same specimen. 



6« and h. A^tMONtTEs Mantelli; from the Chloritic Marl of the Isle of Wight; in the 

 collection of John Morris, Esq., p. 40. 

 6a, side view. 

 6<5, front view. 



Mtt.w'VeTl.cev-emS 



la, b, and c. kMmmv^^ Mantelli ; from the Chloritic Marl of Bonchurcb, Isle of 

 Wight ; in the collection of S. Saxby, jun., Esq., p. 40. 

 la, side view. 

 lb, front view. 

 Ic, outline of septum. 



8. Ammonites* navicularis; outline of the septum of the specimen fig. 1, above. 



