PLATE XXX. 
SILURIAN SPECIES. 
Fic. 
I—8.  Orthis patera, Salter, MS. 1. Exterior of ventral valve. 2. Exterior of dorsal 
valve. 3. Profile of the two valves. 4. Internal cast 
of dorsal valve; 5, of ventral valve. 6. Interior of 
ventral valve, taken in gutta-percha from a cast. 7. In- 
ternal cast of dorsal valve. 8. Interior of the same 
valve. All from Caradoc; Corston Farm; Hopesay. 
Museum Geol. Survey. 
9, 10. »  e@guvalvis, Dav. Wenlock Shale; near Walsall. 10. Interior of 
ventral valve. 
11—21. ,,  vespertilio, Sow. 11. From the original specimen figured in the ‘Silurian 
System.’ Caradoc; Acton Scott. 11d. Portion of 
shell, magnified. Mus. Geol. Soc. 12. Caradoc; Craig 
Head Quarry, Girvan, Ayrshire. 13. Portrane, County 
Dublin. 14—16. Caradoc; Harnage, south-east of 
Shrewsbury. 17. Internal cast of dorsal valve. Caradoc ; 
Acton Scott. Mus: Geol. Soc. (Original specimen 
figured in ‘ Silurian System,’ pl. xix, fig. 7.) 18. Inte- 
rior of the same, taken in gutta-percha from a cast. 
19. Internal cast of ventral valve ; near Bala. 20. Inte- 
rior of ventral valve, taken in gutta-percha from an 
internal cast. Gretton. 21. From Rathdrum, Wicklow. 
Mus. Geol. Survey of Ireland. 
