Silurian Bocks. 85 



the last Anniversary, we have had two hy Professor Sedg- 

 wick on the comparative classification of the fossiliferous 

 strata of North Wales with the corresponding deposits of 

 Cumberland, Westmoreland, and Lancashire, both of them 

 in continuation of his memoir read in November 1843. I 

 will not attempt to give any abstract of the contents of these 

 papers, because I could not do so, to any useful purpose, 

 without extending my observations to an inconvenient length ; 

 but I recommend all who are desirous of acquiring an accu- 

 rate knowledge of the geological topography of those parts 

 of our island, and of becoming acquainted with many facts 

 that throw light on that obscure and difficult part of geology, 

 to study the memoirs themselves; those of 1843 and of 

 March 1845 are published in the first volume of our Journal, 

 and the last of them will appear in the number of next May. 

 It is to Professor Sedgwick we are mainly indebted for the 

 knowledge we possess of the geological structure of those 

 parts of our island ; it was he who first grappled with their 

 very complicated and difficult conformation ; for nearly 

 twenty years he has been labouring to decipher their ob- 

 scure and complex characters; and, since the discovery of the 

 Silurian key, he has been enabled to make out a clear and 

 intelligible outline of the history of these regions, which> for 

 a long time, geologists seemed to shrink from all attempts 

 to understand. Let us hope that the learned author will 

 soon gather together his scattered materials, and bring out 

 a new edition of his work, with all the corrections and illus- 

 trations which his latest observations enable him to supply. 

 When we have that volume, and can study it with the com- 

 mentaries, and the additional illustrations of accurate sections, 

 which we in part have, and may soon look forward to receive 

 from Sir H. de la Beche and his fellow -labourers in the Geo- 

 logical Survey of Great Britain, we shall possess a very full 

 and correct knowledge of these older sedimentary deposits, 

 and the igneous rocks with which they are associated, and 

 therefore of the most remote periods of geological history ; 

 and we may, perhaps, then indulge in a little excusable na- 

 tional vanity of possessing another standard with which the 

 structure of exter^sive and distant regions of the earth will 



