Vie. 
1—7. 
8—12 
15—16. 
17—21 
22—29. 
PLATE XXXIII. 
SILURIAN SPECIES. 
Orthis Carausii, Salter, MS. 1—4. Complete form, drawn from gutta-percha moulds taken 
from external casts. Lower Llandeilo or Arenig rocks ; Tremanhire, near 
St. David’s. 5. Internal and external casts, showing their natural shape in 
a yellow sandstone; from Tremanhire. 6. Distorted internal casts; from 
Ramsey Island, near St. David’s. 7 a. Interior of ventral; 7 6, of dorsal 
valve. 
Menapie, Hicks, MS. From the Lower Llandeilo or Arenig group of Ramsey Island. 
8. Perfect form, from gutta-percha moulds made from external casts. 
9. Distorted internal and external casts. 10. Profile view of both valves. 
11. Internal cast of dorsal valve; 12, of ventral valve. 
Hicksu, Salter, MS. From the Middle (sandstone) beds of the Menevian group or Lower 
Lingula-flags of Ninewells and Porth-y-rhaw, near St. David’s. 13, 14, 
15. Complete form, taken by the means of gutta-purcha from external casts. 
16. Internal cast of ventral valve. 
alata, Sow. 17. After the figure in the ‘Silurian System.’ Llandeilo Flags; Pensarn, 
Caermarthenshire. 18, 19. Complete forms, taken from external casts by 
means of gutta-percha; 18a, enlarged. 20. Internal cast. 21. Portion of 
the shell, enlarged. 
lenticularis, Wahlenberg, sp.? From the Upper Lingula-flags. 22—25. After figures by 
Salter, in vol. iii, pl. iv, of the ‘Memoirs of the Geol. Survey.’ Penmorfa 
Church, Tremadoc. 26. Complete form, drawn from gutta-percha moulds 
taken from external casts. Ogof-ddu Cliff, North Wales. 27. A very large 
flattened specimen from Rhiw Felyn. Mr. Plant’s Collection. 28, 29. 
Gwerny-y-Bareud (“ Dolgelly group” of Belt). 
~~ ™ 
