BRITISH SILURIAN BRACHIOPODA. 211 



Caradoc, at Ballygrot, County Down, Ireland. He states that the fossil occurs also in 

 the Hartfell Shales and Glenkiln Shales of the Moffat Series in Scotland. In general 

 shape and dimensions it much resembles Discina ? BaldetcJiiensis from the Llaudeilo 

 of the Girvan district, but is wanting of the raised ring-shaped margin which surrounds 

 the valves of that species. 



Genus — Obolella, Billings, 1861. 



147. Obolella Sabrin^e, Callaway. Dav., Sil. Sup., PI. XVI, figs. 27, 28. 



Oboleila Sabring, Call. Quart. Journ. Geol. Soc, vol. xxxiii, p. 669, pi. xxiv, 

 fig. 12, 1877. 



Shell small, transversely oval ; upper valve conical ; vertex submarginal \ surface 

 smooth. Slightly more than 1 line in length by nearly 2 in breadth. 



Dr. Callaway remarks that " This species bears a close resemblance to Obolella 

 sagittalis, Salter, of the Menevian Rocks, but is broader, and has the ventral valve more 

 conical ; the median ridge is larger and longer, and the valves are furnished with areas." 

 Also that he " Originally described this form, from incomplete materials under the name of 

 Metoptoma Salrincs ; the conical ventral valve closely resembling a patelloid Gastropod." 

 0. SabrincB occurs in the Tremadoc or Shineton Shales, Mary-Dingle, Dryton, one mile 

 west of Cressage, west of Harley, under Cound-Moor Quarry, and where the fossil is 

 common. 



148. Obolella sagittalis, Sailer. Dav., Sil. Mon., PI. L, figs. 1—14 ; Sup. PI. XVI, 



figs. 25, 26. 



Since describing this species at page 339 of my ' Silurian Monograph,' the fossil has 

 been collected by the Geological Survey of Scotland, along with Discina Portlocki 

 (Geinitz), at Cairn Burn, Druidhill Burn, in Dumfriesshire. It is also quoted by Prof. 

 W. C. Brogger, at page 45 of his Kne work ' Die Silurischen Etagen 2 und 3 im 

 Kristianiagebiet und auf Eker,' 1882, as occurring in Sweden, as well as by Dr. G. 

 Linnarsson in the ' Sveriges Geologisca undersokning,' No. 35, pi. iii, figs. 45 — 49, 

 1879. It seems to be a good species and characteristic fossil. 



