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Proceedings of the Royal Irish Academy. 



lower beds of the Coal Measures strata, says: — "At some of the 

 localities (before alluded to as junction-beds, ante, pp. 14, 22), the 

 lowest of these, immediately over the Carboniferous Limestone, contain 

 a characteristic bivalve aviculoid shell, Posidonomya Becheri, common 

 to the Culm of North Devon, which occurs in profusion in a band 

 of impure limestone or hard black shales, occupying the same position, 

 and being in equal abundance at Garristown and Loughshinny, the 

 overlying shales containing longitudinally-striated plant-remains, and 

 goniatites." 



There can be little or no doubt that the Upper Limestone Shales 

 of County Clare are therefore the homotaxial equivalents of the 

 Pendleside series of the Midlands of England, and belong to altogether 

 a higher horizon than the Yoredales. 



The earlier nomenclature of Coal Measures, although not accurate, 

 was far preferable in Ireland to that of Yoredales, because, no doubt, 

 the series passes up in an unbroken succession to beds of true Coal 

 Measure age. The term " Upper Limestone Shales " seems, I think, 

 to denote an affinity to the limestone in some way, and there is none 

 either palaeontological or lithological. 



It is therefore important to recognise the real position of the 

 Upper Limestone Shales in the west of Ireland, for their fossil 

 contents afford the very strongest evidence of a similarity of conditions 

 extending over an area which includes the east of Belgium and the 

 west of Ireland. And further, the identity of stratigraphical 

 sequence, the similarity of the fauna, and the presence of identical 

 peculiar variations, afford the strongest proof that the homotaxial 

 equivalents were contemporaneous. The Chokier series in Belgium does 

 not appear to be very thick ; and the whole series beneath the grits in 

 County Clare is only 80 feet, so that Clare and Chokier appear to be 

 almost the east and west limits of a basin, the beds of which are much 

 thicker in the centre. 



In the Midlands I have always considered Glypliioceras spirale to 

 occupy a position somewhat high in the Pendleside series ; it seems to 

 occur some distance above the bullions with fossils at Poynes Island ; 

 and G. reticulatum, we know, passes up into the Millstone Grit series. 

 This is evidently the case in County Clare ; but I have no doubt that 

 the olive grits and flags between the shales with G. diadema and the 

 Coalfield, are the equivalents of the Millstone Grits; and in this 

 connection I would mention that in certain localities — e.g., the valley 

 of the Hodder, which separates the Counties of Lancashire and 

 Yorkshire — some of the grits there present similar tracts and 



