Geological Society. 67 



throughout the Mediterranean, but outside that sea not north of Cadiz 

 (lat. 36° 30') ; and two others are new species of this exclusively 

 southern mutabilis-gvoxxp. Another seems to be a rare Italian 

 Upper-Plioceno species of the reticulata-group, N. reticostata, Bel- 

 lardi ; while the sixth is the Lower Pliocene and Upper-Miocene 

 species, N. serrata, Broechi. This shell, in the variety of form it 

 presents at St. Erth (where it is one of the most frequent shells), 

 seems to connect the Red-Crag N. reticosa, Sow., with the Italian 

 N. serrata, while the shorter forms of it are identical with the Italian 

 Lower-Pliocene N. emiliana, Mayer. The fauna is altogether 

 southern, no exclusively Arctic shell having as yet occurred in it. 



The author regards the bed as clearly Pliocene, and inclines to 

 the opinion that it is rather Newer thm Older Pliocene ; that is to 

 say, it is coeval with the Red Crag, but its affinities are more 

 with the Pliocene of Italy than with the Pliocene of the North-Sea 

 region ; and this seems to show that during its deposition there was 

 no communication between the Atlantic and the North Sea, except 

 round the north of Britain, the refrigeration of the water by the 

 nine degrees of latitude, through which Britain extends northwards 

 from St. Erth, preventing the access of the Italian group of Nassa 

 to that sea. This view is also strengthened by the absence of any 

 close agreement between the fauna of St. Erth and that of the 

 not far distant Pliocene of Normandy, the faunal affinities of both 

 the older and newer parts of that Pliocene (the Conglomerat a 

 Terebratules and Marnes a Nassa, regarded by geologists as of the 

 age of the Coralline and Bed Crags respectively) being more with 

 the North-Sea Crag than with the St.-Erth bed. 



As regards the geography of the immediate neighbourhood during 

 its accumulation, the bed is the deposit of a strait that joined the 

 sea on the north of Cornwall (St. Ives Bay) to that on the south of 

 the county (Mounts Bay) ; and which insulated the high ground of 

 the Lands-End district from the rest of Britain. The elevation of 

 the shell-bearing part of the clay, as ascertained for the author by 

 a set of levels run by Mr. Nicholas Whitley of Truro, C.E., who 

 first brought the bed to public notice in the ' Transactions of the 

 Royal Geological Society of Cornwall,' is 98 feet above mean-tide 

 mark in the Hayle estuary, near to it, the surface of the ground being 

 about 15 feet higher. Angular stones of small dimensions (none 

 yet met with by the author exceeding 3 cubic inches) occur occa- 

 sionally in the clay along with the shells, in amount of about one 

 pound to a hundredweight of the clay, indicating, apparently, the 

 drift of coast-ice over the strait during the deposit : bi;t the author 

 has only noticed one rounded pebble in the clay he has searched 

 through. 



Dr. Gwtn Jeffreys expressed his regret that the author of this 

 important communication was prevented by illness from being pre- 

 sent at the meeting, and said that the paper exhibited indications of 

 the great energy possessed by the author notwithstanding his bad 

 state of health. Great credit was also due to Mr. Robert Bell for 



