PLATE XLVIII. 



SILURIAN SPECIES. 

 Fig. 

 1 — 9. LeptdBna transversalis, Dalman. 1,2. Wenlock Limestone; Dudley. 2a. 



Shell-sculpture, enlarged. 3. Wenlock Shale ; 

 Pentland Hills. 4, ba. A very transverse variety (Zl. 

 Duvalii, Dslv.). Dudley. 6. A fragment, enlarged, to 

 show the area, pseudo-deltidium, &c. 7. Interior 

 of the dorsal valve, enlarged. 8. Interior of the 

 ventral valve, enlarged, 9. Area and pseudo-del- 

 tidium in the two valves. 9 a. Internal cast of 

 the dorsal, and 9 d^ of the ventral valve. Pentland 

 Hills. 

 10 — 19. „ sericea. Sow. 10, 11. Sowerby's original figures in ' Sil. 



Syst.' Caradoc ; Whittingstow and Horderley, 

 Shropshire. 12, 12 a. Copied from ' Siluria.' 13. 

 Llanfyllin. 14. Llandeilo Flags ; Llann Mill, Caer- 

 marthenshire. 15. Caradoc ; Pentrefflymru, near 

 Llanfyllin. \b a, b, c. Enlarged. 16. Interior of 

 the dorsal, and 17, of the ventral valve, enlarged. 

 Caradoc beds; Llanfyllin. 18. Internal cast of 

 both valves, enlarged. Desertcreat, Tyrone. Port- 

 lock's Coll., Mus. Pract. Geol. 19. Internal cast 

 of the ventral valve, showing vascular impressions. 

 19 «. The same, enlarged. Caradoc; Haverford- 

 west. Mrs. Branwell's Collection. 

 20 — 22. „ „ var. rhombica, M'Coy. Caradoc ; Moclydd, near 



Oswestry. 

 23 — 27. „ quinquecostata, M'Coy. 23. After M'Coy 's original figure, 'Sil. 



Foss. Ireland,' pi. iii, fig. 8. Tyisaf, Llangedyn. 

 24. Rhywlas, Bala. Both in the Mus. Pract. Geol. 

 24«, 2.5fif. Enlarged. 26, 27. Caradoc; Girvan, 

 Ayrshire. 27 a. Enlarged. 

 28 — 30. „ segmentum, Angelin. 28. Wenlock Shale; Walsall. 2%a,b,c,d. 



Enlarged. Dudley. Gray's Coll. in the British 

 Museum. 30. Interior of the ventral valve, en- 

 larged. 



