308 BRITISH SILURIAN BRACHIOPODA. 



dorsal valve the bifid cardinal process is very small; muscular impressions obscurely 

 defined. 



Length 16, width 22, depth I| lines. 

 Obs. This species is remarkable on account of the very slight convexity and concavity 

 of its valves ; indeed, it is often almost entirely flat, so that the space left free between the 

 valves for the occupation of the animal is exceedingly small. Its ribs, or radii, are also very 

 fine and numerous ; the muscular depressions in the ventral valve are very broad anteriorly, 

 and fan-shaped ; and in this respect peculiar to the species (figs. 19, 20). 



Prof. M'Coy states that the general surface is very coarsely punctate, and marked, 

 especially near the margins, with the external radiating striae. 



Position and Locality. The vertical range of this species seems to be limited to the 

 Wenlock and Ludlow divisions. In the Wenlock Limestone and Shales it is abundant 

 at Burrington, Oldcastle (Murchison's locality), at Dudley, Benthall Edge, Usk, Llan- 

 dovery, Lindsway Bay. At Biyn-mawr, Capel-y-rhiw ; Mynydd Tryfan (in beds above 

 Denbighshire Grits). In the Aymestry Limestone at Leintwardine. In the Upper 

 Ludlow, south-west of Hazle, Woolhope, Bringwood Chase, Ludlow, Burton and 

 Brockton, near Wenlock, Tulithwaite Hall, Underbarrow, Kendal, Westmoreland, &c. 

 Prof. Phillips enumerates also many localities in the Malvern, Abberley, Woolhope, and 

 Usk districts. 



In Ireland it is stated by M'Coy to occur in Upper Silurian rocks at Doonquin, 

 Dingle, County Kerry, and at Ferriters Cove, Dingle. I have not yet seen any Scottish 

 specimens, but expected to have met it in the Pentland Hill section. 



Upon the Continent it has been found in Westrogothia, Gothland. 



D'Eichward states that it occurs in the Orthoceratite Limestone of Tosna, in the 

 Government of St. Petersburgh. 



Strophomena applanata, Salter. PI. XLIII, figs. 12 — 14. 



Orthis (?) APPLANATA, Salter. Synops. Sil. Foss, Ireland, pi. v, fig. 1, 1846. 

 Strophomena — Phillips and Salter. Mem. Geol. Surv., vol. ii, p. 380, 1848. 



— _ Salter. Appendix, Mem. Geol. Surv., Sheet 32, Scotland, p, 



138, 1861. 



— — Haswell. Sil. Form. Pentlands, p. 34, pi. ii, fig. 18, 1865. 



— — Dav. Pal. Trans. Geol. Soc. Glasgow, vol. i, p. 19, pi. ii, 



figs. 19, 20, 1868. 



Spec. Char. Semicircular, much compressed, greatest width at hinge-line. Cardinal 

 extremities prolonged into acutely angular mucronate wings. Ventral valve very slightly 

 convex ; area narrow ; fissure arched over by a small pseudo-deltidium. Dorsal valve very 



