572 Hepoiis and Proceedings — 



Geological Society of London. 



November 5, 1884.— Prof. T. G. Bonney, D.Sc. LL.D., F.R.S., 

 President, in the Chair. — The following communications were read : — 



1. " On a New Deposit of Pliocene Age at St. Erth, 15 miles east 

 of the Land's End, Cornwall." By S. V. Wood, Esq., F.G.S. 



The deposit described in this paper occurs about five miles north- 

 east of Penzance, and consists of a tenacious blue clay with shells, 

 resting on sand, and passing upwards into a yellow unfossiliferous 

 clay, which is overlain unconformably by the earth with angular 

 fragments, under which the ancient beaches of the Bristol Channel 

 (with which beaches, however, the deposit now described has no 

 connexion) are buried. It has been excavated for the underlying 

 sand at intervals during the last fifty years, but has been disused 

 since 1881-82, when it was temporarily worked to supply the yellow 

 part of the clay for the Penzance dock-works. 



The author has got together, partly from corresp)ondents in Corn- 

 wall and partly from his own researches in clay consigned to him, 

 upwards of 40 species of Mollusca, inclusive of a few of which only 

 fragments have as yet occurred, and of several minute species. 

 Among these, besides some that are apparently altogether new, are 

 some particularly characteristic species of the Red Crag not known 

 living, such as Cyprcsa (Trivia) avellana, Sow. ; Melampus pyramidalis, 

 Sow. ; and Nassa granulata, Sow. (or else N. granifera, Dujardin), as 

 well as other characteristic Crag species that still live, but not north 

 of the coast of Spain, such as Turritella triplicata, Brocchi {T. 

 iacrassata, Sow.), and Bingicula huccinea, Brocchi. 



The most interesting featui-e of the fauna, however, consists in the 

 six species of Nassa that the deposit has hitherto j'ielded, of which 

 all but one, N. granulata, Sow. (or g^ram/era, Dujardin), are unknown 

 from any formation of Northern Europe, and occur, whether in the 

 living or fossil state, only in the southern half of Europe.^ One of 

 these is Nassa mutahilis, Linne, which now lives throughout the 

 Mediterranean, but outside that sea not north of Cadiz (lat. 36° 30') ; 

 and two others are new species of this exclusively southern mutahilis- 

 group. Another seems to be a rare Italian Upper-Pliocene species 

 of the reticulata-grou]), N. reticostata, Bellardi ; while the sixth is 

 the Lower Pliocene and Upper-Miocene species, N. serrata, Brocchi. 

 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 i\^. 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 



1 N. congiiobaia, a species of a group near to that of miilahilis, has occurred in the 

 Eed Crag ; but, so far as the author is aware, neither that shell, nor any of the 

 group to which it belongs, has occurred in any other formation of Northern Europe. 



