﻿Vol. 6 I.] OF THE MARINE BANDS IN THE COAL-MEASURES. 535 



field and the Pendleside Series of Bosley Mine. It is important to 

 distinguish it from Pterinopecten papyraceus, for which purpose the 

 following characters may be relied upon : — 



(1) It is a much smaller shell ; (2) its shape is quadrate-subcircular ; 

 and (3) the external ornament and arrangement of ribs. 



Its ribs are broader and much less numerous, the anterior ribs 

 being curved outwards near the lower margin ; the ribs become 

 obsolete over the postero-superior angle of the right valve, and the 

 anterior ears have well-marked radiating ribs. 



Localities. — North-Staffordshire Coalfield : marine band below 

 the Gin-Mine Coal; 71 feet below the Four-Feet Coal, Cheadle. 

 Black shales of the Pendleside Series, Bosley Mine (Cheshire) ; 

 270 feet below Gay Wein Coal, Bristol Coalfield. 



Posidoniella sulcata, Hind, 1904. (PI. XXXV, fig. 16.) 



Posidoniella sulcata. Hind, ' Monogr. Brit. Carb. Lamellibr.' vol. ii, pt. iii 

 (1904) p. 131 & pi. xxv, figs. 2-6. (Pal. Soc. vol. lviii.) 



This shell attains a size of 25 by 35 millimetres, and it is very 

 important to distinguish it from Posidonomya Becheri, which species 

 indicates a zone at the base of the Pendleside Series. Posidoniella 

 sulcata has the narrow hinge-line of its genus, and no anterior ear. 

 Its ornament, consisting of concentric angular ridges, separated by 

 wide, concave sulci, differs from the close, flattened, concentric ribs 

 of Posidonomya Becheri. 



I am of opinion that I saw, several years ago, a specimen of 

 Posidoniella sulcata from the Lancashire Coal-Measures, in the cabinet 

 of the late Mr. Neild, of Oldham, but all attempts to trace the 

 specimen have failed. Mr. H. Bolton 1 quotes Posidonomya lateralis, 

 a synonym of P. Becheri, as occurring in the Lower Coal-Measures 

 of Lancashire. Possibly he may have mistaken a specimen of my 

 species for it. 



Localities. — This species was founded on numerous specimens 

 from the marine band below the Gin-Mine Coal, North-Staffordshire 

 Coalfield. It has also been found 71 feet below the Pour-Feet Coal 

 of Cheadle. 



Posidoniella l^evis (Brown). (PI. XXXV, fig. 17.) 



This species has its maximum in the Pendleside Series, and is not 

 common in the Coal-Measures. I have not been able to observe 

 any characters pointing to evolution in the later specimens. This 

 may be due to the fact that, as it nearly always occurs in shales, the 

 shell is so often crushed. 



Localities. — North Staffordshire Coalfield : above the Stinking- 

 Coal, and with Pterinopecten papyraceus near Froghall Station, in 

 the Cheadle district ; 29 feet above the Seven-Feet Banbury ; below 

 the Gin-Mine Coal. 



Lancashire Coalfield : above the Bullion Mine at Colne, Sholver, 

 Starring, and Dearnley ; above the Gannister Coal, Pimbo, near 

 Wigan ; below the First Grit, Ipstones ; 500 feet below the Third 

 Grit, Congleton Edge. 



1 Trans. & Ann. Kep. Mancb. Microsc. Soc. 1895. 



