Vol. 67.] FATJNAL HORIZONS IN THE BRISTOL COALFIELD. 327 



PELECYPODA. 



Carbonicola acuta (Sowerby). 



Posterior halves of two shells, showing the lines of growth and 

 the hinder end of the hinge-line. Both specimens are crushed flat, 

 and somewhat distorted. 



Horizon and locality. — 1 38 feet below the Bedmiuster Great 

 Yein, South Liberty Colliery, Bristol. 



Carbonicola aqtjilina (Sowerby). 



One specimen ouly of this species was found in shale upon the 

 pit-heap at Easton Colliery. The few other fossils found at this 

 colliery came from the roof-shales of the Kingswood Great Vein, 

 and there is reason to believe that this specimen is from the same 

 horizon. 



Horizon and locality. — Roof-shales of the Kingswood Great 

 Vein, Easton Colliery, Bristol. 



Carbonicola sp. 



A small crushed shell, not more than 3 millimetres ]ong, too 

 indeterminate for accurate description. In its produced anterior 

 border, which bends around the relatively broad umbo and curves 

 in towards the hinge-line, the specimen, notwithstanding its ex- 

 tremely small size, is decidedly of a Carbonicola type. 



Horizon and locality. — 621 feet below the Bedminster Great 

 Vein, South Liberty Colliery, Bristol. 



The absence of Carbonicola, except as one of the rarest of fossils, 

 is a remarkable feature in the Bristol Coalfield. Had it occurred 

 here, as in other coalfields, in such profusion as to form ' mussel- 

 bands,' the fact must have been noted long ago in sinkings. 

 The place of Carbonicola seems to be taken in some degree by 

 Antliracomya. 



Anthracomya williamsoni (Brown). 



Examples of this species are rare. The shell is very thin, and 

 often absent, leaving a smooth-surfaced internal cast. When 

 present, the shell is marked by very fine lines of growth, most 

 evident on the antero-ventral margin. The shale in which the 

 specimens .are found appears similar to that yielding A. phillipsi, 

 but the two species have not been seen in association. 



Horizon and locality. — Second Series of the Upper Coal- 

 Measures, Writhlington Colliery, Radstock. 



Anthracomya phillipsi (Williamson). 



Several fine examples of this species were obtained from a compact 

 black shale, which was recognized by miners as occurring near the 

 Toad Vein at South Liberty Colliery. The outline of the shell 

 in several instances is perfect, and the wrinkled periostracum is 



