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with those formations which have generally heen called transition. 

 And here, gentlemen, many of you well know, that if I had had to 

 address you at a period a little later, I might have hoped to he able 

 to point out, among the labours of our members, some which may be 

 considered as events of primary importance in this part of our know- 

 ledge ; — steps which may be described as a new foundation rather 

 than a mere extension of this portion of European geology ; — a sepa- 

 ration and arrangement of transition rocks, which is likely to become 

 the type and classical model of that part of the geological series, as 

 Smith's arrangement of the oolites became the type of that portion 

 of the strata. I speak of Professor Sedgwick's views on the Cambrian 

 rocks, which occupy the north-west of Wales, and Mr. Murchison's 

 on the Silurian formations which cover the remainder of the princi- 

 pality and the adjacent parts of England. Mr. Murchison's work, 

 which cannot but be one of first-rate value and interest, will, I trust, 

 be in our hands in a few weeks ; and I should grieve to think that 

 Professor Sedgwick will be not only so unjust to his own reputation, 

 but so regardless of the convenience and expectations of geologists, as 

 to withhold from the world much longer the views which his saga- 

 cious and philosophical mind has extracted from the accumulated 

 labour of so many toilsome years, on a subject abandoned to him 

 mainly from its difficulty and complexity. 



Turning then to the researches which have been laid before us 

 upon the earlier stratified rocks, I am first led to notice the important 

 memoir of the two gentlemen I have just mentioned, upon the struc- 

 ture of North Devonshire. According to the views of these gentlemen, 

 founded upon an extended examination of the county, this portion 

 of England forms a great trough, having an east and west position, in 

 which a series of culmiferous beds rest at their northern and southern 

 extremities upon older rocks. The plants found in the culmiferous 

 beds are said to be all identical with species which are abundant in 

 the coal-fields of the central counties of England, and of the South 

 "Welsh coal basin : and it was at first conceived that these plants 

 diff^ered essentially from the scanty and imperfect remains of vege- 

 tables which are found in the older rocks. More recently, how- 

 ever, the same fossil plants which occur in the culm measures are 

 said to have been detected in the subjacent strata. Before this fact 

 was known, the identity of the fossils and the resemblance of mine- 



