692 Professor Sedgwick and R. 1. Murchison^ Esq., on the 



conclusion, we think we may rather be accused of being over-cautious and 

 tardy in accepting- evidence, however opposed to commonly received opinions. 

 But, on this score, we may state in our justification, that a considerable part 

 of our fossil evidence has been but recently brought to light. Several of the 

 organic remains, from the neighbourhood of New Quay, on the north coast 

 of Cornwall, which we owe to the kindness of Mr. Carlyon, and many other 

 good specimens given to us by our friend Mr. Pattison of Launceston, have 

 been but very recently submitted to a careful examination; and the beautiful 

 collection of Plymouth fossils committed to our care by Mr. Hennah, was 

 only unpacked, in consequence of unavoidable delays, during the present 

 spring. An examination of this collection by one of the authors, assisted by 

 Mr. Lonsdale, Professor Phillips, and Mr. James Sowerby, confirmed the 

 previous conclusions of Mr. Lonsdale, which were chiefly founded on Mr. 

 Austen's collection; and, as before stated, led the way to our proposed clas^si- 

 fication of the Cornish and Devonian formations*. 



At first, we did not intend to give any map among the illustrations of this 

 paper ; as it was thought that any of the published geological maps of England 

 would enable the reader to follow our details. But it has now been thought 

 better to give a reduced map of the country we describe, chiefly taken from 

 the corrected Index geological map attached to Mr. De la Beche's Report on 

 the Geology of Cornwall and Devon; in order that we may convey, at a single 

 glance, the connexion between the structure of Devonshire and Cornwall, and 

 the directions in which our several sections are drawn f. All details of structure 

 are, however, intentionally avoided, and the stratified groups are all repre- 

 sented by two colours. In this way we mean to convey our belief, that the 

 inferior groups all belong to one system, viz. that of the old red sandstone. 

 There may, indeed, among the lowest rocks of the two counties, be some 

 which belong to a still lower system. But if such there be, we are unable 

 to point them out ; and we think it best and safest, as far as regards their 

 classification, to merge them all at present in one common colour. 



Neither did we at first intend to publish any figures of the fossils derived 

 from the several groups above described. But it was urged, that a paper pro- 

 posing such great changes in the classification of our older rocks would not 

 be well received, or even understood, without more graphic proofs than mere 



* Since this paper was read, Mr. Williams has permitted us to examine his excellent col- 

 lection of fossils from Cornwall and North Devon. We may allude to them generally as con- 

 firming our views ; but none of them will appear among the illustrations of this paper, as their 

 specific descriptions are, we trust, hereafter to be given by Professor Phillips, 

 t See Plate L. 



