732 ON THE STOCEDALE SHALES. 



previous speakers on their mode of swelling out laterally into normal 

 deposits of great thickness. Hence, although the forms had un- 

 douhtedly migrated from region to region, the time taken for migra- 

 tion was so short, as compared with the time taken for the accumu- 

 lation of an appreciable thickness of sediment, that the film formed 

 during the time of migration might he practically neglected. 



He thanked the Society, on Prof. Nicholson's behalf as well as 

 his own, for the way in which the paper had been received. 



