PLATE VII. 
SILURIAN SPECIES. 2 
Fic. 
1—9. Duscina oblongata, Portlock. Figs. 1 and 2 are drawn from the two original 
specimens figured by Portlock, under the designation of 
“ Orbicula levigata, Minster ;” from the Caradoc beds of 
Desertcreat, Tyrone. Mus. Geol. Survey, London. Fig. 
3, from Caradoc beds of South Shropshire. Collection of 
Mr. D.C, Davies. Figs. 4, 5, from New Girvan, Ayr- 
shire. Geol. Survey Mus. Figs. 6 and 7 are taken from 
Portlock’s original examples of D. subrotunda. Caradoc 
beds, Desertcreat, Tyrone. Mus. Geol. Survey, London. 
Fig. 8, after Portlock’s original figure of D. oblongata 
(‘Geol. Rep.,’ pl. xxxu, fig. 13). Fig. 9, from Barda- 
hessiagh, Pomeroy, County Tyrone. Collection of Sir R. 
Griffith. 
LO. Ss, Morrisii, Dav. From Wenlock limestone, Dudley; and Aymestry 
limestone, Sedgley. Fig. 12, in Mus. Geol. Survey, 
London. 
ies, » ? Vicaryi, Dav. Cast of upper valve; Lower Silurian (?), Pebble-bed, 
Budleigh - Salterton, Devonshire. Collection of Mr. 
Vicary . 
14—18. Orbiculoidea Forbesii, Dav. Figs. 14, 15, two very fine examples of the 
foraminated valve, from Wenlock limestone, Winnal’s 
Farm, Malverns; Mus. Geol. Survey, London. Fig. 16, 
a large, very gibbous upper valve, from Wenlock lime- 
stone, Dudley. British Museum. In fig. 16 a, the lower 
or foraminated valve has been added to show how the 
shell would appear when complete ; under this figure is 
another smaller and perfect specimen. Fig. 17, a small 
example from Wenlock shales, Rushall Canal, near 
Walsall. Fig. 18, from Llandeilo flags, Shelve. Collec- 
tion of Mr. Morton. It is not, however, quite certain 
that this last really belongs to O. Fordesii, although the 
resemblance is great. 
19. » 2  Beckettiana, Dav. Wenlock limestone ?, Wren’s Nest, Dudley. 
Collected and presented to the Mus. Geol. Survey, 
London, by Mr. H. Beckett. 
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