23° 
4. 
6. 
7. 
8. 
9. 
1On Tl: 
12. 
12140115. 
16. 
17. 
18, 19. 
20—22. 
23, 24. 
25, 26. 
a7 31, 
> 
plicata, Sow. 
PLATE XXXV. 
SILURIAN SPECIES. 
Orthis calligramma, Dalman. Caradoc; Moelydd, near Bala. 
Caradoc ; Craig Head, Girvan, Ayrshire. 
Caradoc ; Grangegeeth, County Meath. Mus. Geol. Survey of Ireland. 
Caradoc ; var. with numerous small ribs. Craig Head, Girvan. Coll. of 
Mr. J. Thomson. 
Caradoc; Lamby, Ireland. 
Large Lower Llandovery variety ; Cong, Galway. Mus. Geol. Survey. 
Interior of dorsal valve. Caradoc; Desertcreat, Tyrone. Same Museum. 
Internal casts of dorsal and ventral valves. Grangegeeth, Ireland. 
Very fine internal cast of ventral valve. From the Caradoc of Das Eithen 
Ridge, east of the Berwyn Hills. 
Var. proava, Salter. After figures in vol. iii, ‘Mem. Geol. Survey.’ Upper 
Llandeilo rocks ; Llanerchymedd, Anglesea. 
Var. calliptycha (Sow.), Salter. Id. Caradoc slates; Pembrokeshire. 
(This strongly resembles O. Davidsoni.) 
(O. callactis, Sow.) After the figure in ‘Sil. System.’ 
Var. Davidsoni, De Verneuil. Wenlock Limestone ; Rushall Canal, near 
Walsall. Mus. Geol. Survey. 
Var. Scotica, M‘Coy (Orthisina Scotica, M‘Coy). Caradoc; Craig Head 
Quarry, near Girwan. 20. After M‘Coy’s figure. 
Var. virgata (according to Mr. Salter). 23 and 24a are from figures in 
vol. il, ‘Mem. Geol. Survey.’ Caradoc ; Cwm-Gwynen-Uchaf, Montgo- 
meryshire, Mus. Geol. Survey. 
O. calligramma, var. plicata, Salter. 25. Internal cast of dorsal valve, 
after Salter’s figure in vol. iii, ‘Mem. Geol. Surv.’ Caradoc; Bala. 
26. Caradoc ; south-west of Bryn, Bedwog. Mus. Geol. Survey. 
Sowerbyana, Dav. O. calligramma, var. Walsalliensis, Salter (not of Davidson). 27, 29, 
30. From Mr. Salter’s figures, ‘Mem. Geol. Survey,’ vol. iii. Lower 
Llandovery; Gas Works, Haverfordwest ; and Caradoc of Cefn Liwydlo, 
Brecknockshire. 28 and 31. Specimens from same locality. 
