. LONDON CLAY. 273 



The specimens are from four to five inches long, the shell very thin, 

 and possessing the striated structure observable in the recent species of 

 the genus. The surface is almost smooth, with the exception of a few in- 

 distinct longitudinal ribs, that are decussated by gentle concentric depres- 

 sions formed by the lines of increase. 



9. Vectuncnlns pnlvinatus. (Lamarck.) 



This shell is very abundant; large masses of the limestone being 

 almost whoUy composed of it ; a slab in my possession, about a foot square, 

 contains upwards of fifty specimens. Considerable variety is observable 

 in the form of the shells; some being transversely, and others obliquely 

 obovate, and a few nearly orbicular. They are from 0*5 inch to 1-8 inch 

 long, and are marked by numerous longitudinal stria?, crossed by fine 

 transverse lines ; the marks of increase are distant. The hinge teeth are 

 from fourteen to sixteen in number, and the interior of the margin is finely 

 serrated. 



10. A small tricuspid tooth of a species of squalus. 



11. Large ramose zoophytes; the specimens are in too imperfect a 

 state to be particularized. 



The following shells are enumerated by Mr. Webster, but were not 

 observed by Mr. KoUo. 



12. Calyptrgea trochiformis. Foss. Hant. figs. 1, 2. 



13. AmpuUaria j9a^M/«. 



14. Serpula. 



15. Modiola elegans. Min. Conch. Tab. ix. fig. 5. ;^ 



16. Ostrea edulis. 



17. Teredo navalis. ' 



N N 



