Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/185

 Plate VI.

Fig. 1. Strophomena budleighensis, Dav. Internal cast of ventral valve, natural size.

l a —. —. The same, enlarged.

l b —. —. Interior of same valve, taken by means of gutta percha from cast.

2. Strophomena Edgelliana, Dav. Exterior of dorsal valve.

3. —. —. Internal cast of dorsal valve, natural size.

4. —. —. Interior of dorsal valve, enlarged.

5. —. —. Interior of ventral valve, enlarged.

6. — Vicaryi, Dav. Natural size.

7. —. —. Interior of ventral valve, enlarged.

8. Rouaulti, Dav. Internal cast of both valves, natural size.

9. —. —. Interior of dorsal valve, enlarged.

10. — Etheridgii, Dav. Internal cast of dorsal valve, natural size.

11.—. —. Interior of dorsal valve, enlarged.

12. —. —. Internal cast of ventral valve.

13. Chonetes, sp. ? Internal cast, natural size.

13 a, —. —. ? Enlarged cast.

14. Productus (Leptoena) Vicaryi, Salter, sp. Internal cast of ventral valve, showing cardinal spines and large muscular scars.

Discussion.

Mr. Etheridge agreed with Mr. Davidson as to his determination of the species. He had, however, examined the extensive collection of Mr. Vicary, and, from the general fades of the species, he was inclined to assign them to the Middle Devonian and Lower Carboniferous beds. The attribution of the fossils to the Upper Llandovery beds was founded on the presence of Lingula crumena, &c. ; but he thought he could give some clue to the locality from which the pebbles had been derived. It had at first, from the lithological character of the pebbles as well as from the fossils, been thought that they were of Lower-Caradoc age. He himself assigned the rocks from which the pebbles had been derived to the Hangman group of North Devon. At Anstey's Cove Mr. Tawney had lately found a series of the same class of fossils in a matrix exactly like that of the pebbles. He had examined the spot, and there recognized with Mr. Tawney an extension of the sandstones of North Devon (the Hangman Grits) on the south coast ; and certainly, so far as lithological character was concerned, the rocks were the same as the pebbles. It did not, however, follow that all the pebbles came from that particular district, but probably from the denudation of the large tract of country of Devonian age to the north. There are, however, Silurian species in certain of the pebbles, and these he would refer to the denudation of rocks in an area mainly to the south of what is now the Devon coast. The fauna at Budleigh-Salterton is essentially British, and not French, though some few species are common to both areas. The bivalves, indeed, are hardly known in France. On the whole, Mr. Etheridge concluded that the fossils in the pebbles were Devonian, with a slight admixture of Silurian and probably Carboniferous forms, derived from rocks at no great distance from the spot where the pebbles are found.

Prof. Ramsay pointed out that in conglomerates we might expect