12 



cylindrical root or trunk, growing in this direction, in the 

 soft mud at the bottom of fresh water lakes or seas, without 

 branches, but sending out fibres from all sides : that it was 

 furnished in the centre with a pith of a structure different 

 from the surrounding wood or cellular substance, more dense 

 and distinct at the older end of the plant, and more similar 

 to the external substance towards the termination which 

 continued to shoot." * 



These points being assumed, Mr. Steinhauer says, " the 

 manner in which the reliquiae were formed is easily explained. 

 Annual decay, or an accumulation of incumbent mud, having 

 deprived the trunk of the vegetative principle, the clay 

 would be condensed by superior pressure around the dead 

 plant, so as to form a species of matrix : if this took place 

 so rapidly, that the mould had obtained a considerable de- 

 gree of consistency before the texture of the vegetable was 

 destroyed by putrefaction, the reliquium was cylindrical ; if, 

 on the contrary, the new formed stratum continued to 

 subside, while the decomposition was going on, it became 

 flattened, and the inferior part might even be raised up 

 towards the yielding substance in the inside, so as to pro- 

 duce the groove, or creesh, as Woodward calls it, on the 

 under side, in the same manner as the floor in coal works is 

 apt to rise where the measures are soft and the roofs and 

 sides have been secured. While the principal mass of the 

 plant was reduced to a soft state, and gradually carried away 

 or assimilated with mineral infiltrated matter, the central 

 pith being unsupported would sink towards the underside, 

 and this the more sensibly where its texture was most dis- 

 tinct; whilst its anterior extremity would go into putre- 

 faction with, and be lost in the most tender part of the 

 plant. The mineral matter introduced would now form an 

 envelope round the pith, when this resisted decomposition 



* Trans, of the American Philos. Society, New Series, vol. i. 



