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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Feb. 5, 



have been made available in classifying the strata in which they 

 occurred ; since no distinction of the older palaeozoic formations by 

 means of imbedded fossils had then been attempted. Between the 

 brilliant dawn of Scottish geology and the last few years, the fossils 

 of these old rocks had altogether escaped attention. When, how- 

 ever, Professor James Nicol discovered certain forms in the schists 

 of Peebleshire, he at once saw that they were of Silurian age by com- 

 paring them with the Graptolites published in the f Silurian System.' 

 About the same time, and a few years after the publication of my 

 work upon the Silurian Region, Mr. J. Carrick Moore*, having 

 collected Graptolites in Wigton shire, referred the schists in which 

 they occurred to the ' Silurian System ; ' and Professor Sedgwick, 

 having subsequently visited that region and extended his researches 

 with Mr. Moore, confirmed the view, having first considered the 

 Ayrshire deposits to be Upper Silurian or Devonian f, and afterwards 

 having classed them as Lower Silurian. Following on those researches, 

 and after the publication of his excellent ' Guide to the Geology of 

 Scotland,' Professor James Nicol gave us two memoirs on the Silurian 

 Rocks of Peebleshire J and the Tweed §, in which he assigned strong 

 grounds for believing, that the oldest rocks containing fossils in this 

 region of Scotland were of the age of the Llandeilo group of the Lower 

 Silurian Rocks. Another group of forms having been sent to the Geo- 

 logical Society from the environs of Kircudbright Bay, Mr. Salter 

 pronounced them to be of the age of the Wenlock shale || . 



Having at various periods of my life traversed portions of this South 

 Scottish tract, I had a strong desire to look at it more closely, now 

 that it had been pronounced by others to belong to my own ' Silu- 

 rian System.' I was the more stimulated to do so, by hearing from 

 Professor Sedgwick at the last meeting of the British Association a 

 verbal communication on the highly fossiliferous tract of Ayrshire 

 near Girvan, from which, in addition to collections made there by 

 Mr. J. Carrick Moore, he had procured many fossils, which had then 

 been to a great extent named, and were about to be described for him 

 by Professor M'Coy ; preparatory lists of them being then announced. 

 Knowing that Professor Sedgwick had been so unwell, when he last 

 visited Girvan, that he could not work out with satisfaction to him- 

 self the natural sections of the interesting tract around that town, and 

 also that he could not revisit it last autumn owing to his duties, I re- 

 solved to explore it before I looked at other points in the South of 

 Scotland. Having obtained from my old friend every encouragement 

 to do so (for we were together a few days in the South Highlands), I 

 induced Professor Nicol to join me in these researches, and I need not 

 say how valuable his co-operation proved, in consequence of his hard- 

 earned acquaintance with the eastern and central portions of the 

 South of Scotland. 



Having first examined the clay-slate at the mouth of the Clyde, 

 Professor Nicol and myself repaired to Girvan ; and, after exploring 



* Proc. Geo]. Soc. vol. iii. p. 277. f Ibid. p. 553. 



X Quart. Journ. Geol. Soc. vol. vi. pp. 53 et seg. 



§ Ibid. vol. iv. pp. 195 et seg. || Ibid. p. 206. 



