PLATE VI. 



FIG. 1. A polished slab of Kilkenny marble, which derives its figures from one species of 

 the madreporites which have been called Junci Lapulci. 



2. A species of madreporite of this kind from Derbyshire. 



3. A polished slab of marble, deriving its figured appearances from a smaller species. 



4. A madreporite, found in France, and frequently in Wiltshire, apparently the 



fossil described by Linnaeus as Madrepora Arachnoides. 



5. A fossil madrepore which has been hitherto named Madrepora Pectmata. 



6. One of the stars of the madreporite, Fig. 4, magnified. 



7. A madreporite, the stars of which are very uncommonly formed. 



8. A madreporite bearing much of the appearance of the Madrepora Flexuosa, 



from Bristol. This fossil is coloured by the red ferruginous impregnation 

 which so generally tinges the fossils of this neighbourhood. 



9. A madreporite of a very singukr form and appearance, from near Ingleborough. 



10. A slice of marble from Switzerland, beautifully figured by a fossil madrepore, 



which has been named Madrepora Vermicularis. 



11. A madreporite which has been named Madrepora Fascicularis, and is remarkable 



for the frequency with which its transverse lamellae occur. 



12. Shews the general appearance of a polished section of chert, which is found fre- 



quently in some parts of Wiltshire. In this specimen a cast seems to have 

 been formed, and the coral itself removed: the cast being afterwards impreg- 

 nated with silex. 



13. Is the appearance observable in other specimens of this chert, where the calcare- 



ous part of the madrepore has remained, having undergone the silicious 

 impregnation. 



