PLATE XXIII. 



Fig. 



la, b, c. Ammonites curvatus ; from the Grey Chalk of Ventnor, Isle of Wight ; in my 

 possession, p. 49. 

 la, side view. 

 lb, front view, 

 lc, outline of a septum. 



2. Ammonites falcatus ; outline of the septum of a specimen from the Chloritic Marl of 



Ventnor, Isle of Wight; in my possession, p.. 21. 

 Sa, b, c. Ammonites Salteri; from the Chalk with siliceous grains, Chardstock, 

 Somersetshire ; in the collection of J. Wiest, Esq., p. 50. 

 3a, side view. 

 "6b, front view. 

 3c, outline of a septum. 



4a, b, c. Ammonites Ramsayanus ; from the Chalk with siliceous grains, Chardstock, 

 Somersetshire; in the collection of J. Wiest, Esq., p. 51. 

 4a, view of the left side. 

 4b, view of the right side. 

 4c, front view. 



oa, /;. Ammonites Salteri ; from the Chalk with siliceous grains, Chardstock, Somerset- 

 . shire ; in the collection of J. Wiest, Esq., p. 50. 

 5a, side view. 

 5b, front view. 



6a, b, c. Ammonites Feraudianus; from the Grey Chalk of Ventnor, Isle of Wight; in 

 my possession, p. 52. 

 6a, side view. 

 6b, front view. 

 6c, back view. 



la, b. Ammonites Bravaisianus ; copied from Plate XCI, figs. 3 and 4, of D'Orbigny's 

 ' Paleontologie Francaise, Terrains Cretaces.' p. 52. 



S. Ammonites Bravaisianus; from the Middle Chalk of Dover; in the collection of 

 of S. J. Mackie, Esq. : the specimen has been worn, and the tubercles 

 are nearly all rubbed off, p. 52. 



9. Ammonites Bravaisianus; from the Middle Chalk of Dover; in the collection of 

 J. W. Flower: restored by the artist from a broken specimen, p. 52. 



10a, b, c. Ammonites Wiltonensis ; from the Grey Chalk, near Devizes, Wiltshire; in 

 the collection of W. Cunnington, Esq., of Devizes, p. 53. 

 10a, side view. 

 10b, front view. 

 10c, outline of a septum. 



11a, b, c, d, e. Ammonites Jukesii ; from the hard Chalk of the county of Londonderry ; 

 in the Museum of Practical Geology, p. 53. 

 11a, side view of a fragment, with part of three whorls. ■ 

 lib, side view of the two inner whorls of 11a. 

 lie, back view of lib. 

 lid, section of the whorls restored, 

 lie, part of the outline of a septum. 



