NORTH STAFFORDSHIRE COAL FOSSILS. 201 



ironstone. U. minus (Brong. Foss. Flora, vol. 1, 

 pi. 6) : not rare : New ironstone, Fenton ; Knowles 

 ironstone. 



CONIFERS. 



Carpolithes suleata (Foss. Flora, vol. 3, pi. 220) : Bradwell 

 Wood. 



Dadoxylon Sternbergia : New ironstone, Fenton ; Adderley 

 Green. 



Trigonocarpum noeggerathi : rare : interior of Sigillaria, 

 Marl pit, Joiner's-square, Hanley. 



MOLLUSCA. 



The coal measures of North Staffordshire are rich in 

 many species of Mollusca. Of the Brachiopoda, seven 

 genera and about eight species have been found. 

 During the sinking of a shaft at Longton several years ago, 

 marine forms such as Productus, Spirifer, Chonetes, and 

 Discina were found in the roof of the Gin mine and Bay 

 coals. Previous to this discovery, it was the generally re- 

 ceived opinion that marine fossils were restricted to the 

 lower measures of the British coalfields. It is not our in- 

 tention to enter into the question whether coal is of marine 

 or fresh-water origin : we think the conditions under which 

 coal was deposited were varied. The alternation of marine 

 with brackish or fresh-water beds clearly proves that great 

 and important changes took place during its deposition. We 

 have evidence that during the formation of these coal 

 measures there were periods in which the natural and 

 regular order was interrupted by the introduction of a new 

 o 



