80 REPORT— 1842. 



another year will place the matter in a clearer light, and remove many of 

 the apparent contradictions which at present exist. I have planned many 

 new experiments, and every Member of the Association must be aware that 

 these experiments require much time, and often to be repeated. We have 

 to deal with a subtile agent, and the few results which I have already ob- 

 tained, convince me of the existence of some secret principle in light, which 

 I hope to render evident to the senses by its operations, although it may not 

 itself be sensible to the human eye. 

 Falmouth, June 20, 1S42. 



Report on the Fossil Fishes of the Devonian System or Old lied 

 Sandstone. By Louis Agassiz*, Professor of Nat. Hist, at 

 Neufchatel. 

 Having been requested by the British Association for the Advancement 

 of Science to draw up a report on the Fossil Fishes of the Old Red Sand- 

 stone, I think it. my duty, in the first place, to mention the favourable cir- 

 cumstances which have allowed me to undertake this labour, and under 

 what auspices I have been able to accomplish a part of the important task 

 confided to me. 



It would be very difficult for me to give at present an idea of the limited 

 extent of the knowledge possessed a few years back of the fossils of a for- 

 mation very little known at that time, and which, nevertheless, is found at 

 the present day to extend over a considerable portion of the surface of 

 Europe. But if the rapid progress of discoveries in this field renders 

 the appreciation of their limits almost impossible, I must nevertheless ac- 

 knowledge, above all, that it is to the persevering researches and indefatiga- 

 ble zeal of English geologists that science is indebted for the knowledge of 

 one of the most curious faunas, I might even say one of the strangest, that 

 has hitherto engaged the attention of palaeontologists. When I Visited Scot- 

 land for the first time, in 1834, Dr. Fleming and Messrs. Sedgwick and Mur- 

 chison were the only persons who had signalized fossil fishes in the old red ; 

 the first having described various scales from Clashbinnie, which he consi- 

 dered allied to the sturgeons; while Messrs. Sedgwick and Murchison, as- 

 sisted by Cuvier, Valenciennes, and Pentland, published the description of 

 two new genera of fossil fish from Caithness. The total number of species 

 then determined amounted only to four, and only one of these had been 

 fio-ured. I have already mentioned in various parts of my ' RechercKes sur les 

 Poissons Fossiles,' the numerous communications which were made to me at 

 that time on the subject, principally by Mr. Murchison, Mr. Lyell, and Dr. 

 Traill, who enabled me to increase the number of genera to ten, and that of 

 the species to seventeen, previous to the appearance of Mr. Murchison's great 

 work on the Silurian system. Such was the impetus given to the study of 

 the ancient rocks by the publication of this important work, that on visiting 

 Scotland again in 1840, during the meeting of the British Association at 

 Glasgow, I had occasion to examine, in consequence of communications 

 which were made to me, nearly double .the number of genera, and treble 

 the number of species of fossil fishes, which had all been recently discovered, 

 and had not yet been described. In one of the meetings of the Geological 

 Section, I was, nevertheless, able to draw the attention of geologists and 

 paleontologists to some of the most curious types I had just examined the 

 characters of, forms agreeing so little with all we knew previously in re- 

 gard to fossils, that it was impossible to determine at first sight even the 



