418 



A paper was first read, entitled, *' Notice respecting a piece of 

 Wood partly petrified by Carbonate of Lime ; with some remarks on 

 Fossil Woods, which it has suggested." Bv Charles Stokes, Esq., 

 F.G.S. 



Mr. Stokes lately received from Germany, with a collection of fossil 

 woods, a piece of recent wood, stated to have been found in an ancient 

 Roman aqueduct, in the principality of Lippe, in the Buckeberg, in 

 which some parts are petrified by carbonate of lime, while the remainder 

 of the wood, though in some degree decayed, is not at all mineralized. 

 This fact has afforded an explanation of the peculiarities of some other 

 instances of fossil wood, in which different parts of the specimen pre- 

 sent different appearances. Two other instances are particularly de- 

 scribed : one of silicified wood from Antigua, and one of a calcareous 

 petrifaction from Allen Bank in Berwickshire. In both these cases 

 it is inferred by the author, that the process of petrifaction com- 

 menced simultaneously at a number of separate points, and that it 

 was suspended when only parts of the wood had been petrified. The 

 unchanged parts would then be liable to decay; and in the specimen 

 from Antigua the process has been renewed after this remaining part 

 had decayed in a considerable degree, when that also became silici- 

 fied. In the calcareous petrifaction from Allen Bank (which is de- 

 scribed and figured by Mr. Witham, in his v/ork on the structure 

 of fossil vegetables), the parts which had not been petrified at the time 

 the process was interrupted, have been entirely destroyed by the de- 

 cay which then ensued, and the intermediate spaces have been filled 

 up by the crystallization of carbonate of lime, without the removal of 

 the petrified portions from the positions in which they grew and in 

 which they had become mineralized. 



In the specimen from the Roman aqueduct the petrified portions 

 run in separate columns through the wood, as if conducted down- 

 wards by the vessels or woody fibres. In that from Allen Bank the 

 separate portions are spherical in form and independent of each other j 

 and in that from Antigua they are independent, and though nearly 

 spherical not regularly so. Hence the author infers that a different 

 explanation must be sought for the manner in which the solution of 

 mineral matter was supplied in the first instance from that of the 

 two last. 



The paper notices also the fossil wood from Lough Neagh and 

 Bonn, in which some small parts preserve their texture, although re- 

 maining still unchanged in the midst of the petrified mass. 



The author concludes with a short notice of the different conditions 

 in which the structure of wood is preserved in different specimens, 

 and considers that the condition of the wood has not any influence on 

 the process of petrifaction. 



A paper was next read, entitled, " Further notice on certain pecu- 

 liarities of Structure in the Cervical Region of the Ichthyosaurus " 

 by Sir Philip Grey Egerton, Bart., M.P., V.P.G.S. 



In a former communication* Sir Philip Egerton gave an account 

 * Proceedings Geol. Soc, vol. ii. p. 192. 



