PLATE XLVl. 



SILURIAN SPECIES. 

 Fig. 



1 — 3, 5,6. Strophomena grandis. Sow. 1. Caradoc ; Bardahessiagh, Pomeroy; taken 



from a gutta-percha mould of an external impression. 

 Sir R. Griffith's Collection. 2. From Acton- 

 Scott. The late Mr. Wyatt-Edgell's Collec- 

 tion. 3, 3 a. Interior of the ventral valve. Id. 

 Caradoc ; Acton-Scott, Shropshire. Sir R. Mur- 

 chison's original specimen, in the Mus. Geol. Soc. 

 3 a. The ventral valve, from a gutta-percha mould 

 of the cast fig. 3, slightly restored round the edge. 

 5. Interior of the ventral valve; Acton-Scott. 6. 

 . Internal cast. Mus. Pract. Geol. 



4. Orthis porcata, M'Coy=" OrtJds grandis," Portlock (not of Sowerby). 



4. Internal cast of the dorsal valve. 4 a. Mould in 

 gutta-percha. 4 b. Longitudinal section of both 

 valves. Caradoc ; Pomeroy, Tyrone. Sir R. 

 Griffith's Collection. 



7 — 10. Strophomena compressa, Sow. 7, 8. Upper Llandovery; Daraeroy Bridge, 



Tortworth. 9. Interior of dorsal valve. Mus. 

 Pract. Geol. 10. Internal cast of ventral valve. 

 11 — 14. „ ,, var. Llandeiloensis, Dav. 11, 12. Exterior of the 



valves. Llandeilo Flags ; Llann Mill, Caermarthen- 

 shire. lie. External sculpture, enlarged. 1.3. 

 Interior of dorsal valve. 14. Interior of ventral 

 valve. Mus. Pract. Geol. 



15. ? " Orthis cancellata," Portlock. Geol. Report, pi. xxxii, tig. 19. 



Tyrone. 



16. ? '^Orthis anomala," Sow. ' Sil. Syst.,' pi. xxi, fig. 10. Caradoc; 



Horderley Edge. 



17. ? " Leptana complanata" Sow. ' Sil. Syst.,' pi. xx, fig. 6. Caradoc,- 



Acton-Scott. 

 I have not been able to identify these three last-named shells, or to 

 determine to what species they belong. 



