68 Geological Society. 



his share of the work. After careful examination Dr. Jeffreys re- 

 cognized 50 species among the fossils obtained from the deposit at 

 St. Erth ; but from the number given by Mr. Wood he deducted 5 

 for duplicates, aud one which he thought was not a niollusk. There 

 were thus 44 or 45 species, out of which 11 or 12 are recent and 33 

 or 34 extinct. Of the latter 11 only are known to him from Ter- 

 tiary deposits, 4 being of Miocene age, and all of them Pliocene. 

 2'2 species were unknown to him either as Tertiary or recent. For 

 the accurate determination of the species the collection, when more 

 complete, would have to be critically compared with recent forms, and 

 the necessary allowance made for that slight divergence which was 

 always observable in the shells of species whose existence extended 

 over a long period of time. Dr. Jeffreys thought that the author 

 had not quite sufficient knowledge of recent Mollusca for his deter- 

 minations to be thoroughly accurate. The list of shells needs a 

 careful re-comparison with the species contained in the Tertiary 

 collections of Europe. 



He further remarked that no deposits of Glacial age have hitherto 

 been found in the south of England. He was not clear whether the 

 St. Erth deposit was of older Pliocene or possibly of Upper Miocene 

 age. Nassa serrata, Broechi, was one of the few species in the list 

 identical with Crag forms, namely Buccinum reticosum of Sowerby. 

 The deposit did not seem to him to be connected with any Crag bed. 

 A bed near Antibes, in the South of France, seemed to him to 

 resemble the St. Erth deposit in many of its characters, and the 

 mollusca of these two deposits should be critically compared. 



Prof. Peestwich said that this discovery of Mr. Searles Wood was 

 the most, interesting that had been made upon the southern coast of 

 England for many years. It was the first clear evidence from 

 fossils of a depression in Cornwall since Palaeozoic times, as the beds 

 near St. Austell contain no organic remains. The high- and low- 

 level beaches in Jersey and Guernsey are also unfossiliferous. He 

 felt the same difficulty as Mr. "Wood in correlating the beds in Brit- 

 tany. The beds at Boscq d'Aubigny, in Normandy, present many 

 points of analogy with those of St. Erth. There is the same pre- 

 ponderance of Subapennine and Mediterranean species, with many 

 Crag fossils, but the species arc different. 



Mr. Etheridge thought that the author had been rather hurried 

 in drawing his conclusions, and that more stratigraphical and geo- 

 graphical evidence as to the distribution of the bed, and a careful 

 survey of the neighbouring coast were requisite. He said that Mr. 

 Solly had tried to make out the succession of the clays, and Mr. Bell 

 had done much with the fossils, but no doubt man}- more fossils 

 were yet to be found, and the Foraminifcra, which are numerous, 

 had not been determined. For his own part, he had much faith in 

 Foraminifera, when properly determined, as a means of settling tho 

 age of such deposits. 



