jS Cincifuiati Society of Natural History. 



Stone. In many cases this impression was so distinct that 

 there was no difficulty in recognizing the species. The leaves 

 were tho.se of the .soft maple, one or two species of oak, tulip 

 tree and sycamore. There is here a po.ssibility of the pre- 

 servation of the remains of plants, or at all events of their 

 impress upon stone, had it occurred under more favorable 

 circumstances. But on a pavement, where people were pa.ss- 

 ing constantly, the impressions were worn off and soon disap- 

 peared. The rain, however, did not seem to wash them away, 

 so they were something more than mere surface markings. 



This method of preservation of plants has been noticed as 

 long ago as 1858, and in the Annals and Magazine of Natural 

 History printed in that year,'^- Mr. Chas. Peach publi.shcd a 

 paper in which he speaks of the "Nature-printing" of .sea- 

 weeds on the rocks of one of the Orkney Islands, off the 

 coast of Scotland. The genera and species were easily 

 recognizable from the impressions, these being of a yellowish 

 color on a dark background. Some of the slabs of .stone were 

 two or three feet long and half as wide, lying from one-half to 

 one-third way between tide marks. The .stones were coated 

 with an olive-brown seaweed, Ralfsia verrucosa, and Mr. 

 Peach makes the following remarks in regard to it : 



" This coatinj^ may be likened to the chemical preparation in photog- 

 raphy, the Rat/sia being the sensitive part to be eaten away by its 

 overlying corrosive brother. The impress is thus made and the stone 

 wheji washed by the next flowing tide is cleared of all the vegetable 

 matter, both of the decaying /)cs)fiarcstia and dissolved A'at/'sia : the 

 picture is then beautifully shown (fi.xed) on the light-yellow coated 

 slab. Not onlv does the Des)iiarcstia destroy the Ra/fsia. it also dis- 

 solves some of the rock; and thus, as well as the dejjression left by 

 the \j'ashing out of the alga, it is engrave<l in the stone; and probably 

 this depression is added to, time after time, by the carbonic acid in the 

 sea-water, and thus the more indelible it becomes." 



The writer goes on to state that impressions of this sort 

 are quite common in various geological formations, and con- 

 cludes by expressing the belief that while .some of the many 

 problematical markings may have been produced by annelids 

 and Crustacea, most of them represent algal remains. While 

 we can not agree with this conclusion, the ob.servations of 

 Mr. Peach are of great interest, as indicating a method of 

 preservation of i)lant impressions which has not been gen- 

 erally noticed or comnicnUd ui)()n. 



*3d ser.. vol. ii., pp. so-s-i. 



