360 PROFESSOR GEIKIE ON THE 
naturalist will be able to reduce to smaller numbers. But none the less will 
the name of Acassiz stand in the fore front of those by whom the paleontology 
of the Old Red Sandstone has been worked out. 
In his classic “Old Red Sandstone,” which appeared early in the summer 
of 1841, Hucu MILLER gave a section of the formation as displayed at Cromarty, 
and connected it with the much greater development of the corresponding beds 
in Caithness. He regarded these Dzpterus-bearing rocks as forming the true 
Lower Old Red Sandstone ; while the Cephalaspis flagstones of Arbroath he 
considered to be the middle part of the system ; the Holoptychius sandstones 
forming the upper division. This continued to be the prevalent belief for some- ~ 
where about fifteen or twenty years. MILLER’s graphic descriptions of the little 
known fishes, which he had been among the first to disinter from their ancient 
burial-places, roused the attention not only of professed geologists but of general 
readers all over this country and America, and the name “Old Red Sandstone” 
became at once a household word. He claimed for his favourite group of rocks 
an importance in geological history which had never been admitted, and he 
lived to see his claim fully recognised. The popularity of his work incited 
other collectors to explore the Old Red Sandstone of the north of Scotland. 
Many new species and many magnificent specimens of known ones were 
in this way brought to light. Not afew of these were sent to HucH MILLER. 
His collection was thus enriched by the contributions of other fellow-labourers. 
Conspicuous among those who assisted him in this way was the late RoBERT 
Dick of Thurso—an enthusiast in the study of the Old Red Sandstone of his 
native county, to whom science is indebted for much that is now common 
knowledge regarding the fishes of that formation. Of still greater service have 
been the sedulous and unobtrusive but sagacious labours of my friend Mr C. 
W. Peacu. Probably no one has done so much as he towards working out 
the paleontology of the Caithness flagstones. He has not merely discovered 
several new species of fishes, but has collected diligently from every horizon in 
that series of deposits, and has amassed a vast amount of information regard- 
ing the natural history of the fauna of Lake Orcadie. To him belongs 
the merit of having early perceived the terrestrial origin of the plants of the 
Caithness flagstones. He has generously placed his knowledge at my service, 
and I shall have occasion in a subsequent part of this memoir to avail myself 
fully of it. 
Hitherto no attempt beyond vague generalisations had been made towards 
a correlation of the Old Red Sandstone of the north of Scotland with that 
of other regions. The general belief was that of HucnH Miter, that these 
northern deposits belonged to the lower subdivision of the system. It was not 
until the year 1858 that Sir RopErick Murcuison took up the subject anew, 
and endeavoured to show that the Caithness flagstones could not possibly 

