698 Transactions of the Society, 



the clays from the artesian well-boring at " Large Acres," Selsey, 

 we have found a mass of shells presenting every feature of the 

 series as classified by Lister, and we must defer a more serious 

 study of the genus to a future date when dealing with this well- 

 boring. Some of the most characteristic and robust forms occur 

 in the interior of the shells of the gigantic Pholas which occur 

 in well-defined beds at various points of the coast, as well as 

 among the detrital sand gathered at the base of the Mixon 

 Beacon, whilst the finer and more delicate forms are found among 

 the derived fossils in the shore gatherings in which the species 

 washed from the outlying Eocene mud-banks (" clibs ") are most 

 numerous. Mr. J. J. Lister, F.E.S., has been good enough to look 

 over some of our Selsey specimens, and considers the majority 

 to be N. variolaria (Sowerby), though many nearly approach his 

 species N. Wemmelensis var. elegans. The larger specimens are 

 practically without exception N. laevigata (Lamarck). 



