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was really to deal only with our own district. But he 

 thought it was a wise thing sometimes to extend one's range 

 of Tiew in all departments of science, so as to familiarise 

 ourselves with the phenomena of other regions as well as of 

 our own county. Their first duty was with East Kent ; but 

 in these days of rapid railway trains, travellers could easily 

 become acquainted with other localities than those in which 

 their ordinary sphere of duty lay. He therefore proposed to 

 lay before them some account of a very interesting district 

 which he had traversed during last year, in connection 

 with the subject of his address. And first it might not 

 be out of place to say that " Siluria" was a term given by 

 the great geologist, Sir Roderick Murchison, to that tract 

 of country which contains what were at one time be- 

 lieved to be the earliest stratified rocks. The 

 reason for giving it that name was that the tract was 

 that which was inhabited by the ancient Silurians -a people 

 who occupied a portion of the counties of North Wales, 

 and who under King Caradoc made a gallant stand against 

 the Romans. [Dr. Mitchinson here traced on a geo- 

 logical map the course of the Silurian deposits— stating 

 that they were contained in the counties of Pembroke, 

 Cardigan, Brecknock, Radnor, Shropshire, Hereford, and 

 the entire range of North Wales with the exception of 

 Flintshire.] Siluria was classic ground, inasmuch as it was 

 the site upon which were worked out the Cambrian and 

 Silurian systems. Previous to the researches of Sir Roderick 

 Murchison nothing had been investigated lower than the 

 old red sandstone ; all below this was called grauwacke, and 

 before this distinguished geologist appeared on the field, it 

 was supposed to be impossible to elicit anything like order 

 out of the mass of deposits now called by the name Silurian. 

 Sir Roderick, previously to engaging in the investigations 

 which have been so beneficial to science, consulted his old 

 friend Dr. Buckland as to where he should begin his re- 

 searches, and that gentleman indicated the valleys of Wye 

 and the Usk, which Sir Roderick at once explored. As the 

 result of bis patient labour, he succeeded, partly by tracing 

 the strata under one another, and partly by the fossils cm- 



