PLATE XIX 



(SILURIAN SPECIES. 



Fig. 



1. Pentamerus oblongus. Sow. Cast of ventral valve. Llandovery rock; Penwhapple Glen, Ayrshire. 



Mr. D. J. Brown's Collection. 



2. „ After original figure of P. /tern, Sow. (young of P. o6/o«^Ms). ' Min. Con.,' 



pi. xxviii, fig. 2. 



3. „ Knightii, Sow. Portion of a dorsal valve from Ballyaglish, east of Ferriter's Cove, Dingle, 



County Kerry. Sir R. Griffith's Collection. 

 4 — 9. „ undatus. Sow. 4. Internal cast of ventral valve from Cefn-y-Garreg. Mus. Geol. Soc. 



5. Internal cast of ventral valve. Lower Llandovery; Llandovery. Mus- 

 Geol. Survey. 6. A bivalve specimen, viewed from the front. Lower 

 Llandovery ; Cefn Rhyddan. 7. Cast of ventral valve. Figs. 4 and 6, 

 after the original examples figured in pi. xxi of the 'Silurian System.' Mus. 

 Geol. Soc. 8. Cast, fractured so as to show the small converging dental 

 plates of ventral valve. Noedd-Grug. Mus. Geol. Survey. 8 a, 8 b. In- 

 ternal cast of a ventral valve, showing the vascular impressions. Lower 

 Llandovery; Mathyrafal, Montgomeryshire. Mus. Geol. Survey. 9. In- 

 ternal cast of ventral valve from Guilsfield, N. W. of Welshpool. Mus. 

 Geol. Survey. 



10—12. „ ylobosus, Sow. Fig. 10. After the original figure in ' Sil. Syst.,' pi. xxii, fig. 2a. Lower 

 Llandovery; Gorthoyn Fach, Llandovery. Mus, Geol. Soc, Fig. 11. 

 Another specimen, nat. size. 1 1 a. Enlarged ; from Lower Llandovery ; 

 Castell-Craig-Gwyddon. Mus. Geol. Soc. 12. Internal cast ; from Golden 

 Grove, near Llaudeilo. 



13—21. Stricklandinia lens, Sow., sp. Figs. 13, 14. After the original figures in 'Sil. Syst.,' pi. xxi, fig. 



13; from the Upper Llandovery ; Norbury. Mus. Geol. Soc. 15. Slightly 

 restored figure, from a specimen obtained from the Lower Llandovery ; 

 North of Gorllwynfawr. Mus. Geol. Survey. 16. Internal cast, viewed 

 from the beaks. Upper Llandovery ; Craig-yr-Wyddon. Mus. Geol. Survey. 

 1". Portion of the internal cast of ventral valve. Llandovery; Woodford 

 Green, near Tortworth. Mus. Geol. Survey. 8. Ventral valve. Upper 

 Llandovery; Norbury, Bishop's Castle. Mus. Geol. Survey. 19, 20. In- 

 ternal cast. Upper Llandovery ; Avening Green, near Tortworth. Mus. 

 Geol. Survey. 21. Transverse section, quite close to the hinge. 



22,23. „ „ (Pentamerus microca)nerus,M'Coj.). 22. A fragment, after the drawing in ' Silurian System,' 

 pi. xxi, fig. 12. Llandovery; Lickey, Stafi"ordshire. 23. After the woodcut 

 at p. 210 of M'Coy's 'British Pal. Fossils,' stated to be the internal 

 cast of rostral part of ventral valve, showing the cardinal area and small 

 rostral chamber formed by the converging of the dental lamellae. 



