254 BRITISH SILURIAN BRACHIOPODA. 



Golcugocd, and Bird's Hill, in the Llandeilo district ; at Bettws-y-Coed, Penmachno, in 

 Caernarvonshire ; south-east of Cerrig-y-Druidion, and Glyn Ceiriog, in Denbighshire ; 

 Llanwddyn, Meifod, Llanfyllin, Alt-yr-Anker, Rhiwargor near Llanvvddyn, in Mont- 

 gomeryshire ; east and south-east of Bala Lake, west of Corwen, Maes Meillion south of Bala, 

 &c., in Merionethshire. Mr. Hughes found it in Coniston Limestone (Bala) at Helm Gill 

 Dent in the lake district, also in Coniston shale at Pickering Gill, Cautley Sedberg ; and 

 several other localities are enumerated by Prof. M'Coy at p. 213 of his work on 'Brit. 

 Pal. Fossils :' in the Lower Llandovery at Haverfordwest and Mandinam in Caernar- 

 vonshire ; at Marthyrafal in Montgomeryshire. 



From Ireland a long list of localities has been given by M'Coy at p. 28 of his ' Synopsis 

 of the Sil. Fossils of Ireland,' but I dare not reproduce them all as authentic. Sir R. 

 Griffith has the shell from Stieveroe Rathdrum ; it occurs also at the Chair of Kildare in 

 Caradoc Limestone, as well as at Carrickadaggan, New Ross, and Ballycale, in the County 

 of Wexford, &c. ; but some of these last localities may be in Upper Llandeilo according 

 to Mr. Salter. 



Orthis Lewisii (?), var. Hughsii, Bav. PI. XXXVIII, fig. 26. 



Spec. Char. Shell small, somewhat pentagonal, wider than long, indented in front. 

 Dorsal valve moderately convex, with a deep longitudinal angular sulcus, commencing at 

 the extremity of the umbone and widening as it nears the front, hinge-area narrow. 

 Ventral valve convex ; hinge-line considerably less than the width of the shell, area trian- 

 gular, rather wide ; fissure open, narrow ; beak small, incurved ; surface of both valves 

 marked by about twenty-four strong angular ribs, of which nearly half are due to inter- 

 polation. Interior not known. 



Length 2, width 2^:, depth I line. 



Ohs. This small shell has so much of the shape of Orthis Lewisii that I am almost 

 inclined to consider it a mere variety, with fewer and stronger ribs, of the last-named 

 species, but its geological position is very different. 



Position and Locality. It w^as discovered by Mr. Hughes in 1868, in the lowest 

 Coniston Grits of Helmside Dent, and it appears to have been the only Brachiopod 

 obtained from the Upper Coniston group (^. e. the Coniston Grits and Flags proper) ; 

 another specimen was found by him likewise at Casterton Fell, much higher up in the 

 Coniston Grit, and two or three more in the highest beds of the grit or the passage-bed 

 from the grit to the Barmisdale Shale near Torbay, but these last specimens were too 

 imperfect for correct identification. It is singular that the grits in question yield 

 so few species of Brachiopoda. 



