68 BRITISH SILURIAN BRACHIOPODA. 
Spec. Char. Usually transversely oval, sometimes longer than wide; upper or free 
valve moderately and uniformly convex; no defined apex, the posterior portion of the 
valve being evenly convex up to the margin. Surface marked with numerous fine, 
radiating, raised, sub-equal, thread-like striz, with interspaces of about equal width, the 
surface being also crossed by numerous much finer concentric lines. The raised strize 
radiate from the middle of the posterior margin, and increase in number here and there 
by the interpolation of additional ribs, some of which appear also to bifurcate. The 
lower or perforated valve is very much flattened, shghtly raised only near the middle, 
between the centre of the valve and of its posterior margin; the slit is longitudinally oval, 
rather wide, and extending from near the centre of the valve to its posterior margin ; 
surface ornamented with numerous fine radiating strize, with wider interspaces, the entire 
surface being also very finely concentrically striated. Interior unknown. 
Length 7, width 8 lines. 
Obés. ‘This species is variable in its shape, being either transversely or longitudinally 
oval, and at times almost circular. It is possible that the much larger shell I described 
in 1848 by the name of Dzscina Verneuilii, from the Wenlock limestone, may be a full- 
grown specimen or variety of Sowerby’s species; but as there exists some uncertainty 
upon the subject, it is preferable to retain it provisionally as a species. 
Position and Locality. D. striata is stated by Sowerby to have been found by Sir R. 
Murchison in the Upper Ludlow rocks of Delbury, Shropshire; and it occurs also 
in the same kind of rock at Benson Knot, Kendal, Westmoreland, if the Cambridge 
Museum specimens described by M‘Coy really belong to the species under descrip- 
tion. Phillips and Salter state that it occurs at Henllyn, Pencarreg, in the Builth district 
(‘ Memoirs of the Geological Survey of Great Britain,’ vol. 11, p. 276). 
Discina Verneviuil, Dav. Pl. VI, fig. 5. 
Bullet. Soc. Géol., France, 2nd ser., vol. v, p. 334, pl. iii, fig. 47, 1848. 
Ovate, longer than wide ; upper valve moderately convex; no defined apex; surface 
ornamented very similarly to what we see in Discina striata (type). Lower or attached 
valve almost flat, or very slightly convex posteriorly. The slit or foramen is longi- 
tudinally oval, and extends but a little way from near the middle of the posterior margin 
towards the centre of the valve. Surface ornamented as in D. striata. Interior unknown. 
Length 15, width 13 lines. 
Position and Locality. Jam acquainted with but one bivalve example of this beauti- 
ful shell: it was found by the late Mr. D. Sharpe in the Wenlock limestone of Stoney 
Mill, near Ledbury. The original specimen was presented by Mr. Sharpe to the 
Geological Society. 
