PLATE XII. 



FIG. 1. A fossil body, found near Bath, the surface of which is nearly covered by stelli- 

 form markings, which seem to have been formed by a coralloid resembling that 

 which is observed on the fossil, Fig. 2. 



2. A coralloid fossil, from St. Peter's Mountain, near Maestricht, the nature of which 



has not been determined. This, and the other fossils from this mountain, 

 Fig. 4, 6, 11, and 13, have been considered as casts; but this opinion appears 

 to be incompatible with the numerous fibrillac which exist in this specimen. 

 b, a magnified representation of one of the stellated columns. 



3. A silicious fossil from Essex, apparently of a similar nature with the fossils repre- 



sented, Plate VIII. Fig. 1, 8, and 10. 



4. A coralloid fossil from St. Peter's Mountain, the original nature of which has not 



been determined. 



5. A flint, containing an alcyonite from Southend, Essex. 



6. A coralloid fossil from St. Peter's Mountain, the original nature of which has not 



been determined, a, the appearance yielded by one of its protuberances when 

 viewed with a lens. 



7. A silicious alcyonite from Sewardstone, Essex. 



8. A calcedonic alcyonite from France. 



9. An alcyonite of curious structure, in flint, from Essex; its substance, disposed in 



undulating plicae, appeared to be capable of lengthening and contracting by 

 the extension or the corrugation of its folds. 



10. A silicious alcyonite, found in the neighbourhood of Islington. 



11. A fossil from St. Peter's Mountain. In this fossil the alcyonic structure, already 



noticed in the fossil, Plate X. Fig. 1, 2, 3, and 4, is very evident: at d, is 

 seen the inner side of the superior concave surface, a part of which is shewn, 

 slightly manifested at f' } and at , is seen the flat inferior surface. From the 

 appearances yielded by this fossil, it appears to be probable that the other 

 fossils from St. Peter's Mountain, figured in this Plate, may have all partaken 

 more of the nature of alcyonia thai/ of corals. 



12. A flint, supposed to owe its figure to an alcyonium. 



13. A coralloid fossil from St. Peter's Mountain, the nature of which has not been yet 



determined : the marks on some parts of its surface, as shewn, magnified at c t 

 seeming to point out some resemblance to a microscopic tubipore, whilst the 

 ruder and more numerous forms do not appear ,to be referable to any known 

 form of organization. 



