i3§ 



Shells of the Holderness Basement Clays. 



If this view is sustained, there is no reason to consider the 

 other members of the Bridlington beds as derived. Those I 

 have seen are perfectly fresh and unworn, — a polyzoan (Flustra) 

 and an Echinus (norvegicus ?) may be added to the list. 



The absence of Tell, balthica from the above list is the prin- 

 cipal item against the Chillesford Clay being synchronized with 

 the Bridlington Leda myalis beds, seeing it is so abundant in 

 the Wey bourne and Bure Valley deposits. It may have been 

 passed over as a young Tell, obliqua as I certainly received it 

 amongst a parcel of the latter from Aldeby, recognised as T. 

 balthica by Messrs. Wood, Jeffreys and other conchologists, who 

 rejected it on the ground that being an only specimen, it must 

 have got in to the parcel by accident, a view I objected to at 

 the time as I do now, because in texture, colour and condition, 

 it was not different from the others and unlike those from any 

 of the Weybourne group of deposits. 



I have to thank the Custodians of the Bridlington treasures 

 for the kindly and ready facilities afforded me in the work, 

 and the ' Percy Sladen Memorial Fund ' for assistance in meet- 

 ing expenses incurred in search of material; 



Addendum. 



Since the above was written, I have received from Mr. 

 Kennard, F.G.S., a quantity of material obtained by him from 

 the Leda myalis bed, including Scalaria grcenlandica, Bela 

 (several species), Nucula cobboldice, Yoldia hyperborea or ob- 

 longoides, and others, all of forms occurring in the Bridlington 

 list, numbering up to 40 species. (The Yoldia truncata bracketed 

 in the last line of that list should read Y. hyperborea Lov.). 



Dr. C. T. Trechmann has recently described (Quart. Journ. 

 Geol. Soc.) some remnants of early clays on the Durham coast 

 containing arctic shells and Norwegian rocks of the usual types, 

 apparently of the same age as the Holderness basement clays. 



Naturalist, 



