256 CARBONIFEROUS LIMESTONE BRACHIOPODA. 



minima that it required a comparison of the specimens to distin- 

 guish them, more especially as the spines on the hinge-line of 

 the present species are not often seen ; the carboniferous fossil 

 has more uniform and less branched striae, and they are so much 

 finer than in the Silurian species, that double the number is 

 uniformly found to occur in the same space of half a line near 

 the margin. It is possible that this may prove identical with 

 the Leptana gibberula of my volume on the ' Mountain Lime- 

 stone Fossils of Ireland/ t. 20. f . 11 (which certainly has no 

 relation to my L. crassistria and sulcata, with which M. de 

 Koninck unites it) ; but as I there described the width as rather 

 greater, and do not give the absolute dimensions of the fine striae, 

 I hesitate to unite them without a comparison of specimens. 



Very abundant in a piece of the black upper carboniferous 

 limestone of Derbyshire. 



(Col. University of Cambridge.) 



Lingula latior (M'Coy). 



Desc. Broad-ovate anteriorlj^, gradually acuminated posteriorly ; 

 moderately convex towards the beak, very gradually flattened 

 towards the margins ; sides meeting at the beak at an angle 

 of about 75° ; front wide, semielliptically rounded ; greatest 

 width at about the middle of the length, from whence the 

 posterior end is rapidly narrowed to the beak ; surface with 

 fine, sharply defined, strong, close, elevated, obtuse, concentric 

 strise slightly irregular from occasional branchings and inter- 

 ruptions, crossed in parts by longitudinal microscopic striae. 

 Length 41 lines, proportional width y^^^Q. 



Distinguished from the other described Carboniferous Lingula 

 by the very wide ovate form of its anterior end, and the great 

 comparative length and straightness of the posterior lateral edges, 

 which, by their convergence at so small an angle, give the re- 

 markable posterior attenuation or pointed beak, characteristic of 

 the species. 



Not very uncommon in the black limestone over the main 

 limestone of Derbyshire. 



[Col. University of Cambridge.) 



