PLATE XVI. 
Fia. . 
1. Ptygmatis velox, Witchell. Oolite Marl, Longridge. My Collection. (Page 
221.) 
2a. Ptygmatis Stroudiensis, Witchell. Oolite Marl, Longridge. 2%. The same, 
Swift’s Hill. My Collection. (Page 222.) 
3a, 36. Ptygmatis Cotteswoldie, Lycett. Pea-grit, Longfords. 3c. The same. 
Fragment showing natural section. Lincolnshire Limestone, Dene. 
3d. Thesame. Lincolnshire Limestone, Belmisthorpe. My Collection. 
(Page 222.) 
4a. Ptygmatis Cotteswoldia, Lycett, var. conica, Witchell; type refigured. Oolite 
Marl, Swift’s Hill. Witchell Collection. 46. The same, showing 
section of interior. Oolite Marl, Longridge. 4c and 4d. Possibly 
the same, with worn surface—a common form in the Oolite Marl, 
Longridge. My Collection. (Page 223.) 
5. Specimen of Pfygmatis with the aperture and canal well preserved. Oolite 
Marl, Longridge. My Collection. N.B.—This probably represents 
the true form of aperture in this group. 
6. Ptygmatis, species or variety. Oolite Marl, Swift’s Hill. My Collection. 
(Page 224.) 
7. Ptygmatis ? pisolitica, Witchell. Fragment from the Lincolnshire Limestone, 
Weldon. My Collection. (Page 215.) 
Sa. Ptygmatis Santonis, sp. nov. Oolite Marl, Longridge. My Collection. 84, 
8c. The same. Lincolnshire Limestone, Santon. Jermyn Street 
Museum. (Page 224.) 
Ja. Ptygmatis brevivoluta, sp. nov. 96. The same; specimen cut longitudinally, 
x 2. Clyeus-grit, Barrington. My Collection. (Page 225.) 
10. Ptygmatis ? brevivoluta, x 1%. Lincolnshire Limestone, Weldon. My Collection. 
11. Ptygmatis “ sub-brevivoluta.’ Lincolnshire Limestone, Weldon. My Collection. 
(Page 226.) 
12. Ptygmatis ? bacillus, D’Orb. (rolled fragment). Lincolnshire Limestone, 
Weldon. My Collection. (Page 217.) 
