Fic. 
1—4 
5—17. 
g——2o" 
24—30. 
31—34 
35—38. 
39—42. 
PLATE XXXVI. 
SILURIAN SPECIES. 
Orthis eonfints, Salter. 1. From the original figures, ‘Quart. Journ. Geol. Soc.,’ vol. vii. Llandeilo 
» 
” 
. 
. 
beds ; Bogang, Knochdolian, Ayrshire. 2. Stincher River, Ayrshire. 
3. Bogang. Mus. Geol. Survey. 4. Internal cast of dorsal valve. 
Mullock Hill, Ayrshire. 
Actonia, Sow. 5. Caradoc; Bryn Bedwog, near Bala. Geol. Survey Mus. 6. Moelydd. 
7. Robeston, Pembrokeshire. Geol. Survey Mus. 8, 9, 10, 11, 13, 14. 
After Salter’s figures in ‘Mem. Geol. Survey,’ vol. ili. South Wales, in 
Caradoc ; also from Lower Llandovery specimens in Mus. Geol. Survey. 
12. Llandeilo Flags; Garn Arenigs. Geol. Survey Mus. 15. Interior 
of ventral valve, enlarged ; taken with gutta-percha from an internal cast. 
Caradoc; Bryn Bedwog, near Bala. Geol. Survey Mus. 16. Internal 
cast of ventral valve, enlarged. Caradoc; Chair of Kildare, Ireland. 
17. Interior of dorsal valve. Caradoc; Gas Works, Haverfordwest. 
sagittifera, M‘Coy. 18—20. After figures in ‘Brit. Pal. Foss.,’ pl.in. From the Caradoe 
schists of Aber Hirnant. Woodwardian Museum, Cambridge. 20, 
21. Two large internal casts of dorsal and ventral valves. From the same 
locality and collection. 22. Interior of dorsal; 23, interior of ventral 
valve. Caradoc ; Cwm-yr-acttinen, Bala. 
protensa, Sow. 24,25,26. After Sowerby’s figures of O. Jata in ‘ Sil. Syst.’ Lower Llando- 
very; Llandovery. 27. Internal cast of ventral valve. 28. Internal cast of 
dorsal valve. Lower Llandovery; Golengoed, Llandovery. 29. Internal cast 
of dorsal valve, enlarged. Lower Llandovery ; Troutbeck. Coll. of late Mr. 
Wyatt-Edgell. 30. Interior of ventral valve, enlarged; taken from an 
internal cast with gutta-percha. Golengoed. Mus. Geol. Soc. 
Salteri, Dav. 31, 32. Internal cast of ventral valve. 33. Internal cast of dorsal valve. 
33. The same, enlarged. 34. Interior of the same valve, enlarged; taken 
with gutta-percha from an internal cast. Caradoc; Horderly, Salop. 
Coll. of late Mr. Wyatt-Edgell. 
sarmentosa, M‘Coy. After figures in ‘ Brit. Pal. Foss.’ Schists of Llyn Ogwen. Woodwar- 
dian Museum, Cambridge. 
retrorstriata, M‘Coy. After figures in ‘Brit. Pal. Foss.’ Cerrig-y-Druidion. Wood- 
wardian Museum, Cambridge. 
