[NIE ODUCTORY EXPAN ATION. 
Tux introduction to the first part of the ‘Monograph of the Great Oolite Mollusca’ 
contained an intimation that, with increasing knowledge of the testacea of the Cornbrash 
and Forest Marble, it might eventually be desirable to give an additional monograph, or 
an Appendix to that work. The materials which have latterly been placed at the disposal 
of the writer are so considerable that he has been induced to endeavour to fulfil the 
anticipatory announcement made in 1850, and also to correct some errors, both textual 
and typographical, which occur in the former Monograph. In the execution of his task 
the writer begs thankfully to acknowledge the assistance he has received in the loan of 
specimens from gentlemen whose names will be found mentioned in connexion with each 
of the species illustrated, nor can he omit gratefully to mention the great advantages he 
has derived from the constant opportunities that have been afforded to him of comparing 
the Oolitic fossils of the southern counties with those of Yorkshire, contained in the very 
extensive and choice collection of Mr. Leckenby, of this place. 
ScarborovucuH; September 6, 1861. 
