PLATE XXII. 



SILURIAN SPECIES. 



Fig. 



1 — 7 a. Atrypa '! Headii, Billings (?), var. Angliea. [Genus uncertain.] Caradoc ; Grangegeeth, 

 County Meath. Fig. 1. Nat. size; all the others enlarged. 2 and 7. In. 

 ternal casts of dorsal valve. 3. A gutta-percha mould taken from cast, 

 and showing the interior of dorsal valve. 4 and 6. Internals casts of ventral 

 valve. 5. A gutta-percha mould taken from an internal cast of ventral 

 valve. All in the Mus. Geol. Survey, Ireland. (Mr. Billings informs me 

 that the internal spires in A. Headii are arranged as in Atrypa) 



8 — 8 d. „ „ From the Caradoc of Moelydd, Shropshire, on the borders of Denbighshire. 



Mr. D. C. Davies' Collection, 8. Nat. size. 8 a—d. Enlarged. 



!) — 19 6. Rhynchonella'^. P entlandica, Haswell. Ludlow Rock; Deerhope Burn, Pentland Hills. 9, 10. 



After Salter's original figures in the "Explan. Sheet 32, Scotland," 'Mem. 

 Geol. Survey,' p. 138, pi. ii, figs. 7 and 7 a. Figs. II — 18 a. A series of 

 illustrations showing the external and internal characters ; most of the 

 figures being enlarged. 19. A transverse variety (a cast); from Mr- 

 Haswell's Collection. 19 a. Internal cast enlarged ; 19 5, exterior, enlarged 

 from fossil impression. 



20 — 23. „ ? navicula. Sow. 20 — 20 b. A bivalve example, nat. size, from the Aymestry lime- 



stone; Sedgley, near Wolverhampton. 21. Internal cast of ventral valve, 

 nat. size. 2\a,b. The same magnified. 22. A mould in gutta percha, from 

 an internal cast of ventral valve. 23. Internal cast of dorsal valve. These 

 casts are from the Upper Ludlow ; Coppice Ludlow. Mrs. Branwell's 

 Collection. 



24 — 27. „ defiexa, Sow. 24 — 24 c. Nat. size. 24 c (bis), d. Enlarged. Wenlock limestone ; 



Dudley. Figs. 25 — 27. Three specimens enlarged, and viewed from the front^ 

 to show how variable is the number of ribs on the fold and in the sinus in 

 different examples. All from Wenlock limestone ; Dudley. 



28, 29. Merista or Camarium (?) cymbula, Dav. [Genus very uncertain.] Fig. 28 (small figure), 

 nat. size ; others all enlarged. 29. Internal cast of ventral valve, nat. 

 size. 29a. Enlarged gutta-percha mould taken from the same cast. 

 Caradoc ; Hendre-Wen, Cerrig-y-Druidion. Mus. Geol. Survey. 



