92 Horner's Geological Address. 



completed ; a work of the highest merit, in which the skill 

 with which the anatomy of the singular forms of that earliest 

 creation of fishes is worked out is quite admirable, and which 

 also contains many highly important general views. This 

 work was undertaken at the request, and has been carried 

 out by the assistance, of the British Association, and is one 

 of the many valuable gifts for which science is indebted to 

 that body. 



The history of the old red sandstone supplies a useful 

 lesson to geologists, by shewing them the danger of coming 

 to hasty conclusions, and founding generalizations, on nega- 

 tive evidence. The formation itself was long supposed to be 

 confined to a limited portion of England ; it is now known to 

 extend over large districts in the British Isles and on the 

 Continent of Europe. It is most extensively developed in 

 the northern and western parts of the United States, as may 

 be seen by inspecting Mr Ly ell's Map ; and we learn from 

 Captain Bayfield, that a sandstone which prevails greatly in 

 Upper Canada, and which may be traced all round Lake Su- 

 perior, resting on granite, appears to be of the same age a*** 

 the old red sandstone, or Upper Silurian ; and he also ob- 

 served in the district of Gaspe, at the south entrance of the 

 river St Lawrence, a calcareous sandstone with Devonian 

 characters. It appears, too, from the work of Mr Strzelecki 

 on New South Wales and Van Diemen's Land, published last 

 year, thai the greater part of the palaeozoic rocks he examined 

 in Australia and Tasmania are the equivalents of the DevO' 

 nian series. In like manner, this bed was long held to be 

 barren of organic remains ; Sir Henry de la Beche, in the 

 third edition of his " Manual of Geology," published in ISSS-, 

 which was no doubt brought up close to all that was known 

 at that time, says, " Few organic remains have been dis- 

 covered in thai^ rock.'' When M. Agassiz, in 1833, began 

 the publication of his " History of Fossil Fishes," he knew 

 of none older than the coal-measures, and only a small num- 

 ber in them ; and he tells us, that when he first learned that 

 fishes had been discovered in the old red sandstone, during 

 his visit to ScotJiind in 1834, not more than four species 

 were known. Five years afterwards, when Mr R. Murchi* 



