232 SUPPLEMENT TO THE BRITISH 



4. Great Oolite and Stonesfield Slate. — Some 17 species. Of these, one or two only 

 seem to have lived during the formation of the Inferior Oolite and Fullers' Earth. 



5. Forest Marble and Bradford Clay. — About 11 species, of which 8 are found also 

 in the Great Oolite, and, indeed, these last two small and local divisions should be 

 considered (as is usual) to constitute a part of the Great Oolite formation. 



6. Combrash. — About 12 species and 4 named varieties. 



7. Kelloway rock. — 3 or 4 species. 



8. Oxford Clay. — 5 or 6 species. 



9. Lower Calcareous Grit. — 5 or 6 species. 



10. Coralline Limestone. — 10 or 11 species. 



11. Supra-coralline. — About 7 species. 



12. Kimmeridge Clay. — 6 species. 



13. Portland. — 1 uncertain fragment of a Bhynchonella. 



14. Purbeck. — None. 



Thus, it appears that some 127 species and 24 named varieties have been 

 distributed through the sequence of Oolite deposits ; but, as several of the species are still 

 uncertain, and some may be only the young of others, not many more than 100 well-made- 

 out species can at present be put down to our Oolites ; and, if we add to this number some 

 70 from the Lias, about 170 species will have been correctly established as occurring 

 in our British Jurassic deposits. The Inferior Oolite has furnished by far the largest 

 number, both as regards species and individuals ; and subsequent to that period a very 

 great, notable, and almost sudden diminution is observable in the Oolitic Strata that 

 followed it. It is also from the Inferior Oolite that the largest species have been 

 collected. 



With regard to the Coral Bay, I may here reproduce a few passages taken from 

 Messrs. T. P. Blake and W. H. Hudleston's admirable Memoir on the Corallian Rocks 

 of England, published in vol. xxxiii of the ' Quarterly Journal of the Geological Society,' 

 1877. "The descriptions we have given of the actual development of Corallian Rocks 

 in England shows how inappropriate is the term ' Coral Rag ' as a designation for the 

 whole, anything that could be lithologically called by that name forming but a very small 

 part of the series. ' Coralline Oolite ' is an equally inappropriate term when separated 

 from the rock which it properly describes." The Corallian deposits are regarded by 

 Messrs. Blake and Hudleston as being represented, when complete, by the following 

 series, in ascending order : 



1. The Lower Calcareous Grit. 2. The Lower Limestone or Hambleton Oolite. 

 3. The Middle Calcareous Grit. 4. The Coralline Oolite. 5. The Coral Bag. 6. The 

 Supra-coralline beds . 



We have, however, in our Table reduced these six divisions to three in number. 



