Vol. 6S.] PALEONTOLOGY OF THE WAEWICKSHIEE COALFIELD. 631 



It is noteworthy that in this list of freshwater lamellibranchiata 

 there is a complete absence of those forms, such as Carbonicola 

 rohvsta, which in other coalfields are restricted to the Lower Coal 

 Measures. And, further, all the species recorded above are common 

 Middle Coal-Measure fossils. This suggests that the Productive 

 Coal Measures must be of Middle Coal-Measure age — a conclusion 

 whicJi agrees with that arrived at from a study of the fossil 

 flora. 



The marine fauna. — The bulk of the Coal-Measure sediments 

 of this coalfield were undoubtedly laid down in fresh water, and 

 the abundant remains of a terrestrial flora which they contain indi- 

 cate the proximity of land throughout the time that elapsed during 

 the deposition of the beds. Bat, during one period, the subsidence 

 was of such an extent that the sea invaded the area, and the 

 deposits thus formed contain marine forms of animal life. 



This marine bed occurs in the roof of the Seven-Feet Coal ; it 

 consists of dark-blue shale, containing hard ovoid nodules of clay- 

 ironstone. Fossils are found both in the shale and in the ironstone ; 

 but in the former they are usually crushed flat, while in the 

 latter uncrushed specimens may sometimes be found. The marine 

 shale, which contains a large amount of pyrite disseminated through 

 it, has a characteristic mode of weathering quite diff'erent from 

 that of ordinary non-marine Coal-Measure shales ; and this is 

 accompanied by the formation of selenite, which usually occurs as 

 radiating masses of crystals. The ironstones are but little afiected 

 by exposure to the atmosphere, and thus it has been possible ta 

 collect fossiliferous nodules from the waste-tips of collieries which 

 have been abandoned for at least 30 years. The marine horizon 

 has been found at the following seven collieries : — 



Valley Colliery. Pooley-Hall Colliery. 



Glascote Colliery. Alvecofce Colliery. 



Amington Colliery. Hockley-Hall Old Pit (abandoned). 



Birch Coppice, No. 1 Pit (abandoned). 



The marine bed thus appears to be invariably present immediately 

 above the Seven-Feet Coal, throughout the whole of the northern 

 portion of the coalfield.^ 



In the south, at Blackatree Farm, near Wash-Lane Bridge, 

 Nuneaton, an old trial-shaft sunk on the outcrop of the Thick Coal 

 yielded a small amount of dark-blue shale containing fish-remains 

 and Lingula mytiloides Sow. As this shale comes from the bottom 

 of the shaft, some distance below the Thick Coal, it is probably 

 from the Seven -Feet Coal marine bed. The fossils from this 

 stratum are tabulated in the following list : — 



^ Another marine bed may be present above the Thick Coal, but on this 

 point palgeontological evidence is still incomplete. 



