158 
to evince how little information on this point had been obtained at 
that period. 
“ The main consideration concerning these figured stones, which I 
call rock plants, is, whether they are parts of plants or animals petrified, 
or lapides sui generis, to which latter opinion I incline. Indeed, the 
figured roots, on which these rock plants sometimes grow, (as appears 
by the impressions of rays on their tops, answering to those in the 
joints of the plants, and by the impressions of oval joints there,) may 
give us some suspicion that they once belonged to an animal, whether 
it were a species of the Stella arborescens, or some other; but those 
trunks of stone plants (entrochi) cannot be looked upon as parts of 
animals, with the least show of probability ; and I think them almost as 
hardly reducible to any known species of vegetables."'* 
But it would be, indeed, endless to enumerate the various con- 
jectures, which have been formed respecting these bodies; by sonxe, 
they were supposed to be the vertebrae of some species of cartilagi- 
nous fish ; by others, they were concluded to be mere capricious forms of a 
sportive creation. 
It remained for the intelligent and indefatigable Rosinus, to supply 
us with accurate information respecting these bodies ; and to place 
before us a correct sketch of their numerous species. Aided by his 
labours, by the remarks of Mr. Walch, and by those specimens which 
I may happen to possess, I shall now place before you an account of 
such of these bodies as appear to me to be most necessary to be particu- 
larly noticed. 
The TRociiiTiE are spathose circular stones, of different thicknesses, 
with fiat, concave, or convex surfaces, with various markings, and pierced 
with a central hole. These we may divide into those, the central 
hole of which is circular ; and those in which the central hole is poly- ' 
gonal ; and then may distinguish them again by the markings on their 
* Philosophical Transactions, Vol. XIII. P. 277. 
