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PROCEEDINGS 0E THE GEOLOGICAL SOCIETY. 



Yoredale bed v ) with the prepared Scotch list, and found that 32 

 species were not known in Scotland, and that about 60 species ran 

 through or were common to the three Scotch divisions, and also 

 that 28 were found in the Scotch upper and middle series only, 10 

 being found only in the lower series. This community of 28 species 

 corroborates Mr. Hull's views, who believes that geographical posi- 

 tion, through an interposed Silurian barrier, separated the Scotch 

 and English marine areas. There can be no doubt also that over 

 the whole of the north of England and the borderland of Scotland 

 shallow-sea, estuarine, and land conditions largely prevailed during 

 the earlier, if not the middle, Carboniferous stages. It is by such 

 conditions that correlation is rendered difficult overextended areas; 

 and only by patient, long-continued work with a definite end or pur- 

 pose, changes both on the dip and strike being carefully mapped 

 or recorded, can the subdivision of one region be actually compared 

 with that of another. It is from this want of uniformity in working 

 that various horizons are adopted for the same beds by different 

 authors, and that ranges of fossils are made to differ also. A very 

 important table is appended to Mr. Hull's paper, giving the census 

 or known fauna and vertical range of the marine genera and species 

 of the Gannister beds (stage E). All these species are embodied in 

 the numerical estimate in my own table. 36 genera and 69 species 

 are enumerated by Mr. Baily; all the genera aiid 40 species ascend 

 upwards or come from the underlying Carboniferous Limestone. 

 Mr. Baily determines that only 6 species of the 69 pass to Stages F 

 and G. They are Goniatites Listeri, G. Looneyi, Conularia quadri- 

 sulcata, Aviculopecten papyraceus, Discina nitida, and Productus 

 scabricidus. No marine shells occur in the Upper Coal-measures in 

 the table, Sjpirorbis carbonarius and Anthracosia only characterizing 

 the Stage G. Baily also states that 18 species are peculiar to Stage 

 E, or the Gannister beds *. 



Professor Hull in his paper gives a table of the " Continental 

 equivalents of the British Carboniferous divisions," and a table also 

 of " Representative Carboniferous formations," both of great use in 

 classification. A fourth table is added, showing the vertical range 

 of the marine genera and species of Stage F (Middle Coal-measures). 



Plants. — Large as the Devonian flora of America appears to 

 have been, it bears no comparison with the succeeding Carboniferous 

 group, either in America, Britain, or Europe. 95 genera and 

 about 320 species constitute the whole of the known Devonian 

 Plantse, through the universality of their distribution. That much 

 of the Carboniferous flora was derived from the Devonian is evident. 

 Of the 84 British Carboniferous genera, 36 occurred in the De- 

 vonian, and these are also the most typical or marked in the 

 Carboniferous system. 



We owe our chief knowledge of the Devonian and Carboniferous 

 flora of North America to Dr. Dawson, of Montreal, Yanuxem, 

 Hartt, Rogers, Lesquereux, Newberry, and others, who have largely 

 added to the literature of the fossil flora of the American Continent. 

 * Quart. Journ. Geol. Soc. vol. xxxiii. pp. 613-651. 



