114 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 22, 



H. B. Helix hispida, Miill. 



H. B. pulchella, Miill. 



B. concinna, Jejfr. 



H. B. Pupa marginata, Di^ap. 



H. B. Planorbis glaber, Jeffr. (Eanging from Sweden to Madeira.) 



H. B. vortex, Linn. 



H. leucostoma, Michaud. (P. spirorbis of some authors.) 



B. nautileus, Lightfoot. 



B. marginatus, Miill. 



H. Limmea peregra, Midi. 



H. B. aurieularia, Linn., var. acuta, Jeffr. 



H. B. stagnalis, Linn. (Var. Helix fragilis, Montagu.) 



H. B. truncatula, Miill. 



H. , dwarf var. 



H. palustris, Brap. 



H, B. Ancylus fluviatilis, Miill. 



B. oblongus, Miill. 



"The nature and condition of the shells from the Harrowden 

 Pit show that, in all probability, the area formed part of the site of 

 a large lake or piece of fresh water, having a sandy bottom and 

 banks ; that it was situated very near an estuary or flat sea-shore ; 

 and that a small stream flowed into the lake at its upper end from 

 a hill of considerable eminence. The lake must have had water- 

 plants in it and rushes or flags {Iris pseudacorus) at its margin. I 

 assume that all the shells came from one and the same stratum. 



" The area of the Biddenham Pit did not apparently form part 

 of the site of the same lake as at Harrowden ; but it was, in all 

 probability, a smaller piece of water, with more weeds in it. In 

 other respects, as well as in its being the receptacle of a small stream, 

 the conditions appear to have been the same. I take for granted in 

 this case also that all the shells last named came from only one 

 stratum. It may be a question as to whether both these pieces of 

 water existed at the same time. This must in some measure depend 

 on the relative position of the fossiliferous strata in each of the 

 pits in which the shells were found. The occurrence of Hydrohia 

 marginata in the Biddenham Pit is interesting. See Sir Charles 

 LyeU's Paper in the Quarterly Jommal of the Geological Society 

 " On the Crag Districts of Norfolk and Suffolk," and the Appendix to 

 Searles "Wood's ' Monograph on the Crag MoUusca,' published by the 

 Palseontographical Society. I lately noticed it in the freshwater 

 bed at Mundesley, while in company with Mr. Prestwich. It has 

 never been found alive in this country." — J. G. J. 



2. On some Flint Arrow-heads (1) from near Baggy Point, North 

 Devon. By N. Whitley, Esq. 



[Communicated by J. S. Enys, Esq., F.G.S.] 

 (Abstract.) 



Beneath the surface-soil (at the depth of 18 inches from the top) 

 above the " raised beaches " of North Devon and Cornwall, the 



