1853.] 



RAMSAY LOWER PALiEOZOICS OF N. WALES. 



161 



in being more angular at the extremities ; in this and its straight 



dorsal edge, it nearly approaches the form of Leper ditia. 



T>^ TTTT fl r T, 11 fExternal surface of right valve : 



rL. Vll. ng. 5. rull-grown. j i i j ^^ . 



Fiff 6 Youne form i "' ^.^""'^^ ^"^^^ ' ^' anterior ex- 



° ^ ' l^tremity; «,nat. size; 6, magnified. 



Beyrichia simplex, n. s. 



Broadly ovate, globose, smooth ; ventral border rounded ; dorsal 

 border somewhat angular ; hinge line oblique, about two-thirds the 

 length of the valve ; dorsal sulcus faintly marked on the anterior 

 half of the valve. This is closely related to Beyrichia Logani * and 

 to B. stranyulata, M'Coy, apparently forming a passage between 

 this genus and Leperditia. Abundant in the same rock with B. 

 Bussacensis . 



Pl. VII. fig. 7. Cast of the right valve : a, nat. size ; b. magn. 



EXPLANATION OF THE PLATES. 



Plate VIL 



Fig, 1. Illsenus giganteus, Burm. 



Fig. 2. Placoparia Zippei, BoecJc, sp. 



Fig. 3. Dithyrocaris ? longicauda, 

 Sharpe; n. sp. 



Fig. 4. Ogygia ? glabrata, Salter ; n. sp. 



Fig. 5. Beyrichia Bussacensis, Jones, 

 n. sp. 



Fig. 6. 1 , young. 



Fig. 7. simplex, Jones ; n. sp. 



Fig. 8. Disteichia reticulata, Sharpe ; 

 n. gen. & sp. 



Fig. 9. Synocladia Lusitanica, Sharpe; 

 n. sp. 



Fig. 10. hypnoides, Sharpe; n. sp. 



Fig. IL Pecopteris leptophylla, Bun- 

 bury ; n. sp. 



Plate VIII. 



Orthis Ribeiro, Sharpe ; n. sp. 



exornata, Sharpe ; n. sp. 



Bussacensis, Sharpe ; n. sp. 



Berthoisi, Rouault. 



Mundae, Sharpe ; n. sp. 



Fig. 6. Poramboniteslima,;S'/2a»'^e;n.sp. 

 Fig. 7.' Ribeiro, Sharpe; n. sp. 



Fig. L 

 Fig. 2 

 Fig. 3 



Fig. 4 

 Fig. 5 



Fig. 8. LeptaenaBeirensis,5'A«>7?e; n.sp. 

 Fig. 9. ignava, Sharpe; n. sp. 



Plate IX. 



Fig. 1. Redonia Deshayesiana, Rouault. 



Fig. 2. Duvaliana, Rouault. 



Fig. 3. DolabraLusitanica,iSAarj»e; n.sp. 

 Fig. 4. Nucula Costse, Sharpe ; n. sp. 



Fig. 5. Cise, Sharpe ; n. sp. 



Fig. 6. Ribeiro, Sharpe ; n. sp. 



Fig. 7. Ezquerrse, Sharpe; n. sp. 



Fig. 8. Leda Escosurae, Sharpe ; n. sp. 

 Fig. 9. Nucula Maestri, Sharpe ; n. sp. 



Fig. 10. Eschwegii, Sharpe; n. sp. 



Figs. 11,12. Beirensis, Sharpe; n.sp. 



Figs. 13, 14 Bussacensis, Sharpe; 



n. sp. 

 Fig. 15. Modiolopsis elegantulus,-S^arjae; 



n. sp. 

 Fig. 16. Cypricardia Beirensis, Sharpe ; 



n. sp. 

 Fig. 17. Ribeiriapboladiforinis, i'Aarjoe; 



n. gen. & sp. 

 Fig. 18. Pleurotomaria Bussacensis, 



Sharpe; n. sp. 

 Fig. 19. Theca Beirensis, Sharpe; n.sp. 



April 20, 1853. 



Robert Death, Esq., and Arthur Phillips, Esq., were elected Fellows. 



The following communications were read : — 



1 . On the Physical Structure and Succession of some of the 

 Lower Paleozoic Rocks of North Wales and part of 

 Shropshire. By Prof. Andrew C. Ramsay, F.R.S., F.G.S. 

 With Notes on the Fossils, by J. W. Salter, Esq., F.G.S. 



The Sections to which this notice refers are on a scale of 6 inches 



* Referred to by me in Mr. Logan's Paper on Canada, antea, vol. viii. p. 207. 



