ADDENDA AND ERRATUM. 



The two following groups were omitted from their proper places 

 in the list of divisions that have been proposed : 



Leptochrondria Bittner, 1891. Type, P. (L.) oeoUcus from the Trias of Asia Minor. 

 Proposed as a subgenus of Pecten. 



Deltopecten Morris, 1892. Type, D. Illawarensis M., from the Permo-carboniferous 

 of Queensland. Described as intermediate between Pecten and Aviculopecien. 



Page 78, line 22. For Mulleri read striatus. 



