96 



BRITISH SILURIAN BRACHIOPODA. 



considerably in shape and number of ribs ; and I am informed by Lindstrom, that in 

 Gothland it is not uncommon to meet examples showing every passage from forms 

 with large acuminated ventral valves and almost flat areas, to others wherein the area is so 

 narrow that the beaks are almost contiguous. In Dalman's and Hisinger's figure, the 

 area is unusually large and triangular. Sometimes our British specimens are as long as 

 wide ; and, when in fine preservation, the delicate longitudinal and concentric lines give to 

 the shell under the lens a finely imbricated appearance. This is especially the case in 

 casts. Prof. M'Coy states, that in casts the two dental plates in the ventral valve are 

 thick and short ; and that a faint trace of the mesial septum exists on the ridge of the 

 dorsal valve. 



This form more nearly resembles some specimens of Sovverby's Spirifer octoplicatiis, 

 than it does either Spirifera sulcata or Sp. crispa ; and I am therefore not astonished that it 

 should sometimes have been referred to the Carboniferous species. Indeed, some Devonian 

 specimens seem undistinguishable from the Silurian shell. In 1848 M. de Verneuil and 

 myself thought we could identify Spirifer spuriits, Barrande, with the shell under description; 

 but I am not quite certain as to the correctness of this view. Sp. plicatus} Sharpe ('Quart. 

 Journ. Geol. Soc.,' vol. iv), has also been considered a synonym of Spirifera elevata ; and 

 the specimens described and figured in the 'Palaeont. New York,' vol. ii, p. 261, pi. liv, 

 figs. 2 a, b, under the designation of Spirfer sulcafus, appear to me much more like 

 Spirifera elevata than the shell to which they have been referred by Prof. James Hall. 

 I am likewise quite at a loss to understand what can have induced Mr. Sowerby to 

 identify the broken cast of Spirifera in ' Sil. Syst./ tab. iii, fig. 13, with Beltliyris 

 ptychodes, Hisinger {' Leth. Suec.,' pi. xxi, fig. 8), and Dalman, ' Acad. Handl.,' tab. iii, 

 fig. 5), to which it bears no resemblance. Sovverby's example above referred to belongs 

 to Spirifera elevata; and his mistake has also been reproduced in Morris's ' Catalogue of 

 British Fossils;' and by Phillips and Salter in the 'Mem. Geol. Survey,' vol. ii, p. 293, 

 1848. Salter corrected it in ' Siluria.' 



Position and Locality. Spirifera elevata ranges from the Upper Llandovery to the 

 Ludlow Rocks. It occurs in the Upper Llandovery beds at Damory Bridge, Tortworth ; 

 in the Wenlock Limestone of Dudley ; Benthal Edge ; Wenlock Edge ; May Hill ; Wool- 

 hope ; Slate Mill, Hasguard, very large and fine (Salter) ; the Bell, Walsall ; Hereford 

 Beacon ; north of Canwood ; Dormington Wood and Lindel's Green, in the Woolhope 

 district. It occurs not uncommonly in the Llandovery beds at May Hill and Huntley 

 Hill, &c. Also in the Wenlock Shale of Marloes, and of Dingle, Co. Kerry ; in the 

 Lower Wenlock (or Denbigh) grit-beds of Modwl Eithin, of Plas Madoc, and east of 

 Merchlyn and Llanrwst, North Wales ; and at Marloes, Milford, Freshwater, Llaudeilo, 

 Llangadoc, and Llandovery, in Wenlock beds (Salter's MS. Catalogues). 



In the Lower Ludlow beds, at Hole Farm, in the Abberley district ; Dowlas, Coed-y- 



' Orlhis plicala, Vanuxem, Report, p. 112, fig. 1, a. 



