BRITISH SILURIAN BRACHIOPODA. 209 



Cottage, west of Harley, under Cound-Moor Quarry, and Pedwardine. Common." 

 (Callaway.) 



Length 5, breadth 4 lines. 

 The Shineton Shales form part of the Tremadoc Series. L. NicJioIsoni is found 

 associated with Oholella Sahrincs, Callaway. 



Genus — Discina, LamarcJc, 1819. 



142. Discina Caerfaiensis, Hicks. Dav., Sil. Sup., PI. XVII, figs. 37, 38. 



Discina pileolus? Hicks. Quarterly Journal Geol. Soc, vol. xxvii, pi. xv, figs. 12 

 12 a, 1871. 

 — Caerfaiensis, Hicks. Popular Science Review, new series, 1882. 



Shell small, circular ; upper valve conical ; vertex situated at about a third of the 

 length of the shell from the posterior margin. Surface marked with concentric lines of 

 growth. 



Length and breadth about 2 lines. 



Obs. — Only one specimen of this small shell was obtained by Dr. Hicks from the 

 red rocks at the base of the purple slates and shales or Middle Caerfai Group = Lowest 

 Cambrian of St. David's, in Wales. It is the oldest species known to me of the genus, 

 and is found in company with Lingulella primava and L. ferruginea. Dr. Hicks, in 

 1871, did not describe his species, but gave two figures of the shell, and referred them 

 with uncertainty to I), pileolus. In 1882 he distinguished it by the name of 

 Caerfaiensis, and presented the type to the Woodwardian Museum, Cambridge. 



143. Discina oblongata, Portloch. Dav., Sil. Mon , PI. VII, figs. 1 — 9; Sil. Sup., 



PI. XVII, figs. 43—46. 



This species has been found by Mrs. R. Gray to occur in great abundance in 

 the Llandeilo at Balcletchie and at Ardmillan Brae, Girvan, Ayrshire. A specimen 

 also, which I cannot distinguish from it, was found by the same lady in the Upper 

 Caradoc at Drummuck, near Girvan. 



