122 Mr. Weaver on the Older Stratified 



logist should strictly examine that quarter, and give us the 

 result of his researches. But in such an occurrence there ap- 

 pears to be no real novelty, as analogous relations have been 

 stated to exist in some parts of the continent*. 



Should Professor Sedgwick and Mr. Murchison, or Pro- 

 fessor Phillips, as proposed, execute the plan of a full de- 

 scription and figuring of all the undescribed fossils met with in 

 the Older Stratified Rocks of Devon and Cornwall, they will 

 add greatly to the obligations already conferred on geology 

 by their valuable labours. And with respect to North Devon, 

 it may not be immaterial to bear in mind the observation of 

 the former gentlemen, that some of the organic exuviae met 

 with in tlie calcareous slates at Linton, which lie low down in 

 the series, are specifically similar to others appearing in the 

 uppermost part of the series, namely, in the Trilobite slates 

 at Barnstaple f. This task, when accomplished, will put to 

 the proof to what extent these tracts agree or disagree witii 

 other transition tracts hitherto described. 



In now turning again to Ireland, I do not advert particu- 

 larly to die concluding paragraph of Professor Sedgwick and 

 Mr. Murchison % (hi which they refer to certain observations 

 made in Ireland by Mr. Charles W. Hamilton), for this 

 simple reason, that I do not clearly comprehend their appli- 

 cation ; and Mr. Hamilton's paper I have not seen. There 

 appears to me some confusion of terms in the case. 



But Mr. Murchison having in his Silurian system, (pp. 580, 

 5S1,) indulged in some strictures in disparagement of the 

 conclusions to which I had been led in the South of Ireland, 

 I feel called upon to offer the following in reply ; first giving 

 the statement of the author. 



The remarks of Mr. Murchison refer more particularly to 

 the great band of limestone that stretches past Cork, which 

 is intercalated among the transition rocks of that quarter; on 

 which he observes, " Mr. Weaver arrives at the conclusion 

 that a large number (between 60 and 70 species) of the fossils 

 of the transition and carboniferous systems are identical. 

 My zoological data and inferences are completely at variance 

 vk'ith those of Mr. Weaver." That is, of course, taking the 

 Silurian system as a standard measure of all other transition 

 tracts. But it has already been seen that, however highly 

 pleased with the Silurian system itself, I am not content to 



* For some instructive details on this subject, the reader may consult 

 Mr. De la Beche's Report on Cornwall, &c. pp. 132 — 136. 

 f Lond. and Edin. Phil. Mag., vol. xiv. p. 244. April 1839. 

 X Ibid. p. 260. 



