A MONOGRAPH 



THE CRAG MOLLUSCA, 



WITH 



DESCRIPTIONS OF SHELLS 



l-'KOM THE 



UPPER TERTIARIES OF THE BRITISH ISLES. 



BY 



SEARLES Y. WOOD, F.G.S. 



VOL. II. 



BIVALVES. 



LONDON: 



PRINTED FOR THE PAL.EONTOGRAPHICAL SOCIETY. 



1S50— 165G. 



