450 ME. H. BOLTON ON A MAKINE FAUNA IN THE [ISToV. I907, 



The whole bed was exceedingly fossiliferous, large masses extracted 

 at every 14 inches, from the top of the bed to the bottom, showing 

 the same fossils in profusion. Perhaps the most striking feature 

 of the fossils is their dwarfed condition, scarcely any showing 

 evidence of a robust habit. The dwarfing is especially a dominant 

 feature among the fish-remains, the teeth of Diploclus and Pleurodus 

 and the fish-scales, for example, being unusually small ; Pterino- 

 pecten does not reach the same stage of development as that which 

 may be seen elsewhere, while the goniatites were apparently 

 possessed of a thin shell unable to resist crushing. Most of the 

 goniatites are therefore found crushed flat ; and, even where this is 

 not the case, the inner whorls are gone and their place is occupied by 

 a mass of slickensided shale. A feature which the bed shares with 

 no other Coal-Measure shale, so far as I am aware, is the abundance 

 of gasteropods. The whole of the Coal-Measure period seems to 

 have been unfavourable to gasteropodan life, and the remains of 

 gasteropods have hitherto been rare in every coalfield. In this 

 shell-bed, however, they are abundant, although of small size — 

 more than a hundred being obtained from the masses of shale ex- 

 amined. There seems to be an entire absence of the brackish-water 

 mollusca, such as Carbonicola, Anthracomya, and Naiadites, although, 

 as I have already noted (p. 445), examples of all of these genera 

 have been doubtfully recognized in the Radstock Coal-Measures. 

 Remembering their prevalence in the lower beds of other coal- 

 fields, their absence at Ashton Yale is singular. 



The brachiopods, such as Chonetes and Productus, show modifi- 

 cations as contrasted with the same species in the Carboniferous 

 Limestone, which can only be regarded as progressive along those 

 lines of mutation that Dr. A. Vaughan has shown to obtain in the 

 Carboniferous Limestone. 1 



Some 60 feet below the ' Smith's Coal ' lies the ' shell-bed,' near 

 the upper part of which occurred traces of a crinoid in the form 

 of small elongate columnals, while about a dozen examples of 

 Raphistoma radians were obtained, a gasteropod only known 

 previously in this country from below the Gin-Mine Coal of North 

 Staffordshire, and from 500 feet below the Third Grit at Congleton 

 Edge in Cheshire, 2 although it is a well-known fossil in the Belgium 

 coalfields. 



The occurrence of this rare gasteropod below the Gin Mine as 

 well as at Ashton Yale is significant, inasmuch as it agrees with 

 the strong parallelism which can be drawn (as we shall see later) 

 between the Gin Mine of North Staffordshire and this ' shell-bed ' 

 of Ashton Yale on general palseontological grounds — a parallelism 

 which was recognized at once and pointed out to me by Dr. Wheelton 

 Hind. 



1 ' On the Palseontological Sequence in tbe Carboniferous Limestone of the 

 Bristol Area ' Quart. Journ. Geol. Soc. vol. lxi (1905) pp. 246-47. 



2 Dr. Wheelton Hind, ' On the Palaeontology of the Marine Bands in the 

 Coal-Measures ' ibid. p. 532. 



