THE CORALLIAN ROCKS OF ENGLAND. 405 



Corallian are very variable, showing frequent fossil and mineral 

 changes ; but in France we have a physical basis denned by well- 

 marked fossils capable of being traced on the one hand into York- 

 shire, and on the other hand into Dorsetshire, and thus furnishing a 

 means of correlating the two English areas. 



Prof. Morris spoke of the high value of the paper, as the first 

 complete treatise on the Corallian of England, and pointing out so 

 clearly the great difference in the conditions of deposition of the 

 formation in the northern and southern areas, and the mingling of 

 conditions in the central area. He pointed out that the so-called 

 Corallian occupied different zones in different localities on the Con- 

 tinent, stretching, in fact, from the Oxfordian to the Portlandian 

 inclusive. Oppel regarded the Corallian as part of the Oxford group, 

 and the Supracorallian of the authors as a part of the Kimmeridgian. 



The President remarked that the conditions under which the de- 

 posits had been formed were evidently those of a shallow sea. 



The Authors, in reply, said that they had intentionally omitted 

 all references to continental deposits while our own beds were so 

 imperfectly known. They had considered that the term Coral Pag 

 should be restricted to certain beds which are actually such ; and 

 they had correlated southern English beds with Phillips's Yorkshire 

 Calcareous Grit, but had thought it desirable to give them distinct 

 names. Their intention in the paper was simply to give a thorough 

 description of the rocks between the Oxford and Kimmeridge Clays, 

 wherever these might be* 



