158 



to evince how little information on this point had been obtained at 

 that period. 



61 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 some, 

 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 par- 

 ticularly noticed. 



The TROCHIT^ are spathose circular stones, of different thicknesses, 

 with flat, 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. 



