Vol. 6S.'] ¥XL3iO:STOL0GY OF THE WARWICKSHIRE COALFIELD. 629 



known to occur in the Upper Coal Measures. It is clear, therefore, 

 that this is an Upper Coal-Measure flora. The abundance of 

 Pecopteris polymorjyha in the Keele Beds is evidence of their Upper 

 •Coal-Measure age. 



In the Haunchwood Sandstones we have a mixture of forms. 

 Tlie Upper Coal-Measure species P. pohjmorjjlia, which is very 

 rare at this horizon, occurs, together with an abundance of such 

 typical Transition species as JSleiiropteris scheuchzeri, N. ovata. 

 JS^. rarineruis, and Sphenophyllum emarginatum. The Haunch- 

 wood Sandstones must, therefore, be referred to the 

 Transition Series, in which the red xiuneaton Clays 

 may also be placed. 



The striking contrast, between the rich flora of the Middle Coal 

 Measures and the meagre flora of the Transition Series and the 

 Upper Coal Measures, raises an important question with regard to 

 the meaning of this difterence. The partial extinction of the 

 Middle Coal-Measure species of plants, and the incoming of the 

 Upper Coal-Measure Pecopterids and Conifers (which are essentially 

 Stephanian species ranging upwards into the Permian), appears to 

 have taken place during the period of formation of the jN"uneaton 

 Clays. At the same time the abundant fauna of the Middle Coal 

 Measures becomes reduced to a few species of fishes, ostracoda, and 

 Spirorbis. We may expect such profound palfeontological changes 

 to have been accompanied by important changes in the lithological 

 €haracters of the deposits then in course of formation, and, in fact, 

 such is the case. 



The jSTuneaton Clays mark the appearance of the first red 

 sediments among the grey rocks of the Coal Measures. In these 

 red strata are found the first Espley Rocks and Spirorbis Lime- 

 stones, while rocks foreign to the coalfield now become common 

 as pebbles in the breccias. These breccias in the ISTuneaton Clays 

 suggest that a local unconformity may occur at this horizon, an 

 opinion which receives some support from the fact that there is in 

 Warwickshire no equivalent of the Black-Band Group of Korth 

 Staffordshire. In conclusion, it may be affirmed that the 

 horizon of the Nuneaton Clays marks the initiation of 

 those continental conditions in the English Midlands 

 which continued throughout Permian and Triassic 

 times. 



(B) The Fossil Fauna. 



In addition to the fossil flora recorded above, the Middle Coal 

 Measures have also yielded evidence of an extensive fauna. In 

 this paper it is not proposed to describe these fossils in detail : 

 it seems desirable, however, to refer briefly to them, not only on 

 account of the extreme rarity of some of the species, but also 

 because the fauna as a whole may be expected to provide further 

 evidence regarding the age of the beds. The collection includes 

 fishes, Crustacea, and mollusca. 



