70 BRITISH CARBONIFEROUS BRACHIOPODA. 



the two or three fragments in his possession. This material has enabled me to satis- 

 factorily develop and represent the internal details of the ventral valve (PI. XIV, 

 figs. 6, 7, 8) ; but all my efforts have hitherto proved ineffectual in making out those of 

 the dorsal one. 



Zoc. Gyrtina septosa was discovered by Professor Phillips and by Mr. Salmond in 

 the carboniferous limestone of Riddle Head, Burtonfell, Cumberland, and in the Museum 

 of Practical Geology will be found a fine and instructive series of young and middle-aged 

 specimens from the carboniferous limestone of Park Hi!l, Longnor, Derbyshire, as well as 

 an internal cast (PL XIV, fig. 10), discovered in red dolometic limestone, at Ashby de la 

 Zouch. The species has also been collected from the lower scar limestone of Settle, 

 Yorkshire, by Mr. Burrow. 



On the Continent, Professor De Koninck procured a few imperfect individuals in the 

 carboniferous limestone of Vise, in Belgium, where the shell is, as in England, among the 

 rarest species. 



I am not acquainted with any Scottish examples, nor have any been hitherto discovered 

 in Ireland, if C. dorsata, M'Coy, be not a variety of the shell under description. 



Cyrtina dorsata, M'Coy, &c. PL XV, figs. 3, 4. 



Cyrtia doesata, M'Coy. Synopsis of the Carb, Limest. Fossils of Ireland, p. 13G, pi. xxii, 

 » fig. 14, 1844. 



Spec. Char. Subrhomboidal, nearly twice as wide as long ; dorsal and ventral valves 

 evenly convex ; beak of the dorsal valve (our ventral) large, straight ; cardinal angles very 

 large, triangular, slightly concave ; mesial fold indistinct or none ; surface coarsely and 

 regularly striated longitudinally. 



"Length 2 inches, 4 lines; width 2 inches, 10 lines; height of cardinal angle 1 inch, 

 3 lines."— ilfCoy. 



Ohs. As the original example figured by Professor M'Coy covdd no longer be found, 

 and that the only other specimen, possessed by Mr. Griffiths, was in a very fragmentary 

 condition, I could not determine to my entire satisfaction, the relationship of this form 

 to C. septom, but of which it may after all prove but a variety. The ribs seem, however, to be 

 more numerous, simple, and of smaller proportions. The sinus and mesial folds are obsolete, 

 and the general shape less transverse than in the specimens of Phillips's species that have 

 come under my observation. I have therefore provisionally described C. dorsata under 

 a separate head, where it had better remain until the discovery of more ample material 

 will have confirmed or invalidated its specific claims. 



Loc. The only two specimens hitherto recorded were obtained from the carboniferous 

 limestone of Cork, in Ireland. 



