Fic. 
1—16. 
17—19. 
20—27. 
30—39. 
PLATE IV. 
SILURIAN SPECIES. 
Lingulella Davisii, Salter. Figs. 1, 2, Lower Lingula-beds, Pen-y-Bryn, five miles north of 
Dolgelli. Mus. Geol. Survey, London. Figs. 3—7, 9, 13, 14, 13, 
figures of different specimens, reproduced from vol. iii, pls. ii and iv of 
‘Mem. Geol. Survey, London,’ Lingula-beds, North Wales. The speci- 
mens are in the Mus. Geol. Survey, London. Fig. 8, Upper Lingula-flags, 
Tremadoc. Collection of Mr. Morton. Figs. 10, 11, elongated spe- 
cimens, distorted by cleavage. Lingula-flags, Penmorfa, Tremadoc. Maus. 
Geol. Survey, London. Fig. 12, from Bellewstown, County Meath. Mus. 
Geol. Survey of Ireland. Fig. 13, distorted examples, formerly referred 
to Tellinomya. Fig. 14, internal cast, nat. size. Fig. 15, portion of same, 
enlarged. Fig. 16, interior (enlarged), from a mould in gutta-percha 
taken from an internal cast. 
Obolella ? Phillipsii, Holl. Fig. 17, nat. size. Fig. 17 a, 6, c, the same enlarged. Hollybush 
Sandstone (Middle Lingula-beds), Malvern District. Collection of Dr. 
Holl. Figs. 18, 19, two valves from same locality and collection. 
», | plumbea, Salter. Figs. 20, 21, after original figures (‘ Mem. Geol. Survey,’ vol. iii, 
pl. xis). Figs. 10, 10 a, Lower Landeilo Rocks, west of Stiper Stones. 
Figs. 22, 23, internal cast, showing muscular impressions. Hell Pool, 
Wyeford, Builth. Fig. 24,alarge example. Figs. 21—24, in Mus. Geol. 
Survey, London. Figs. 25, 26, from Shelve. Collection of Mr. Morton. 
? Salteri, Holl. Figs. 28, after original figures, ‘ Quart. Journal Geol. Soc.,’ vol. xxi, 
p- 102; Upper Lingula-beds, near Coalhill, end of Malverns. Fig. 29, 
Upper Lingula-flags, White-leaved Oak, near Malvern. Collection of Mr. 
Wyatt-Edgell. 
Obolus Davidsoni, Salter. Fig. 30, a bivalve example, slightly restored. Wenlock shale, 
near Dudley. Fig. 31, interior of ventral valve. Fig. 32, interior of 
dorsal valve from moulds in gutta-percha, taken from internal casts. 
Figs. 33—35, internal casts of the two valves, Wenlock shales, Rushall 
Canal, near Walsall. Mus. Geol. Survey, London. Figs. 36, 37, casts ; 
same locality. Collection of Mr. L. P. Capewell. Fig. 38, another 
cast from same locality. Mus. Geol. Survey, London. Fig. 39, from 
Wenlock Shale, near Dudley. 
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