270 DR. H. HICKS ON THE MORTE SLATES, AND [May 1 896, 



EXPLANATION OF PLATES X. & XI. 

 Plate X. 



Figs. 1-4. Lingula mortensis, sp. nov. 3 a . Enlarged portion of shell, showing 

 ornamentation. Fig. 5. Probably young specimens of the same 

 species. Mullacott, Shelfin, and Morte Point. Author's Collection. 



Figs. 6-8. Stricklandinia lirata, Sowerby. Mullacott Quarry. 6, Collection of 

 the Rev. G. F. Whidborne ; 7 and 8, Author's Collection. 



Figs. 9, 10. Crania, sp. Mullacott Quarry. Author's Collection. 



Plate XL 



Figs. 1-4. Bhynchonella Lewisii (?), Davidson. Barricane, in Morte Bay. 

 Author's Collection. 



Fig. 11. Bhynchonella, Stricklandi (?), Sowerby. Mullacott Quarry. Author's 

 Collection. 



Figs. 5 & 6. Spirifera Hamlingii, sp. nov. Barricane, in Morte Bay. Author's 

 Collection. 



Figs. 7-10. Orthis rustica, Sowerby. Mullacott Quarry. Author's Collection. 



Figs. 12 & 13. Stricklandinia, sp. Mullauott Quarry. Author's Collection. 



Figs. 14 & 15. Modiolopsis barricanensis, sp. nov. Barricane, in Morte Bay, and 

 Mullacott Quarry. Author's Collection. 



Figs. 16 & 17. lHerinaa mortensis, sp. nov. Mullacott Quarry. Author s 

 Collection. 



Fig. 18. Avicula, sp. Barricane. Author's Collection. 



Fig. 19. Cardiolainterrupta(?), Sowerby. A fragment, much enlarged. Mulla- 

 cott Quarry. Author's Collection. 



Fig. 20. A fragment of a Crustacean (carapace ?). Author's Collection. 



Discussion. 



The President said that six years had elapsed since the Author 

 attacked the problem of the rocks of North Devon and their 

 succession. On the former occasion he obtained a verdict of 

 * not proven/ After further careful work on these beds, the 

 Author now came forward with additional evidence from the field 

 and from the fossils derived from the rocks to prove that his 

 reading of the succession of the Devonian rocks is the true one. 

 He (the President) invited discussion (1) on the stratigraphical, 

 and (2) on the palaeontological evidence. 



Prof. Hughes believed that the thickness of the several divisions 

 of the Devonian had been greatly exaggerated, and that the vertical 

 distance of the beds, now proved by Dr. Hicks to be fossiliferous, 

 from the known fossil-bearing beds of Hele, for instance, was not 

 really great. He thought that, although the lithological difference 

 between the main mass of the Morte Beds and of those which 

 occurred on either side of it was very great, there were alternations 

 of the sandy and slaty type in the contiguous strata. In so 

 disturbed an area faults would be apt to occur where rocks of 

 unequal resisting-power were crushed together, and this, with 

 the overfold of the anticlinal arches, might give a deceptive 

 appearance of an unconformable junction. The proof of the theory 

 proposed by the Author depended chiefly upon the palaeontological 

 evidence. Taking the more important test-fossils laid upon the 

 table, namely, Cardiola interrupta, Stricklandinia lirata, and the 



