Mr. C. W. Peach on Nature- Printing of Sea-weeds. 53 



Rev. Mr. Mackay of Rhynie. They are very curious and very 

 puzzling; but though some of the specimens present the ap- 

 pearance of a continuous midrib, that throws off, with a certain 

 degree of regularity, apparent leaflets, I am inclined to regard 

 them rather as lying within the province of the ichnologist than 

 the fossil botanist." From never having seen any of my friend 

 Mr. Mackay's " puzzling specimens," I am unable to give an 

 opinion about them ; but, from the tenor of the whole passage, 

 of which I have only quoted a part, I should be inclined to give 

 them to the botanist. The absence of organic matter, with the 

 midrib and hard fernlike appearance, weigh greatly with me; — 

 for, as with the fossil, so with the beautiful Stromness forms, 

 no portion of the vegetable can now be seen. There is plenty 

 of proof that the pictures now presented to your notice were 

 made by plants. I tried, on my return home, the experiment of 

 laying a piece of Desmarestia on a stone from the beach, and 

 exposed it in the hot sun, keeping it moistened with sea- water ; 

 and although the plant was far gone in decay, and the stone 

 not prepared, and also too pale and siliceous, I succeeded in 

 getting a faint impress, — quite distinct enough to show that, 

 with better materials, success would be certain. I have since 

 ascertained that one of the lady algologists of Pomona, long ago 

 aware of these markings, had succeeded fully, with the splendid 

 materials there, in getting them delineated in the way I tried. 

 One thing, however, we do know, — that land-plants, as well as 

 sea-plants, existed in the Lower Old Red Sandstone period: as 

 regards the former in Caithness and Orkney, it is only lately an 

 acknowledged fact. Plants, principally of the sea, also existed 

 in the Silurian period ; and, as tides ebbed and flowed and the 

 sun shone in both periods as now, why might not the Algae be 

 cast on their exposed and ripple-marked rocks, and their like- 

 nesses indelibly printed, and, on the next flowing tide, the type 

 swept away, leaving no trace of organic matter behind ? I wish 

 most distinctly to be understood, that I do not insist on claiming 

 all dendritical markings on and in rocks for the botanist, for I 

 know that some of these doubtful markings are caused by infiltra- 

 tion, and very many by the sportive arborescent forms of minerals ; 

 add to these, those from the crawling of Crustacea, the wriggling 

 of Annelides, and the tracks of the vegetable-feeding Mollusca, 

 all playing their part in the puzzling drama. I must, however, 

 after acknowledging all these, and striking the balance, still 

 think there is a probability that the printing process has thrown 

 off the greatest number. 



I have delayed sending this to you, in the hope of finding 

 some notice of such a process beyond the very short one which 

 I forwarded, at the time of the discovery, to the British Associa- 



