310 BRITISH SILURIAN BRACHIOPODA. 



commencing at variable distances from the beaks, and extending to the margin ; con- 

 centric hnes of growth few in number. In the interior of the ventral valve there is 

 a small hinge-tooth on each side of the fissure ; the muscular impressions assume the 

 shape of two elongated oval depressions, notched in front, and surrounded by a narrow 

 raised elevation. A small median ridge extends from under the fissure for about 

 one third of the length of the valve. In the interior of the dorsal valve the cardinal 

 process is bifid, each lobe being scooped out along the middle ; on either side of these 

 are the hinge-sockets, margined and separate from the cardinal process by a narrow 

 projecting lamella or ridge. Muscular impressions obscurely defined ; four longitudinal 

 rounded ridges extend a little way from under the cardinal process towards the centre of 

 the valve. 



Length 7, width 9, depth 1 line. 



Obs. This elegant smallish species was named ornatella by Messrs. Salter and 

 Lindstrom, but neither of them described or figured their species. It had been 

 often mistaken for young examples of Strophomena filosa, but from this it is easily dis- 

 tinguishable both by its external sculpture and by the shape of its muscular and other 

 internal impressions. It is a much smaller species, and the radii are comparatively 

 stronger. It varies according to the length of its hinge-line, this last being shorter in 

 some specimens than in others. 



Position and Locality. StropJiomena ornatella occurs in great abundance as internal 

 casts and external impressions in the Upper Ludlow at Whiteclifi" and Coppice, Ludlow. 



In the Island of Gothland it was found by Dr. Lindstrom with its shell almost 

 complete ; but there it is an uncommon fossil. 



Strophomena Waltoni, Bav. (sp.). PI. XLII, fig. 11. 



LEPTiENA Waltoni, Dav. Lond. Geol. Journ., vol. i, pi. xxvi, fig. 3, 1847; and Bull. 

 Soc. Geol. France, ser. 2nd, vol. v, p. 317, pi. iii, fig. 6, 1848. 



Spec. Char. Semicircular, regularly concavo-convex, broadly rounded ; hinge- Hue 

 a little shorter than the breadth of the shell ; area narrow ; pseudo-deltidium small. 

 Ventral valve slightly convex ; dorsal valve gently concave. Surface of both valves 

 marked by numerous, fine, radiating, thread-like striae, with a still finer raised line in 

 the interspace between each pair of the larger striae. Interior not known. 

 Length 9, width 11, depth I fine. 



Obs. This species was discovered by Mr. Walton in the Wenlock Shales at Falfield. 

 Several other examples were likewise collected by Lord Ducie. 



