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. 



3a and b. Ammonites navicolaris ; from the Lower Chalk of Chardstock ; in the collec- 

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

 3a, front view. 

 3b, side view. 



4a and b. Ammonites Mantelli ; from the Grey Chalk of Boncbnrch, Isle of Wight ; in 

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

 4«, side view. Sec. Mb""**' *& > P-^H> l^W 5 



4b, front view. 



5a, b, and c. Ammonites navicularis ; from the Lower Chalk of Chardstock ; in the 

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

 5a, side view. 

 5b, front view. 

 5c, front view of the inner whorl of the same specimen. 



6a and b. Ammonites Mantelli ; from the Chloritic Marl of the Isle of Wight ; in the 

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

 6a, side view, f M«« - «be*c«1«t« ! **' ' 



Qb, front view. 



7a, b, and c. Ammonites Mantelli ; from the Chloritic Marl of Bonchurch, Isle of 

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



la, side view. jfaHHU ' ^ € t 



lb, front view. 



1c, outline of septum. 





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



