( 835 ) 



On the Structure of some Fossil Woods fotmd in the Island of 

 Mull, Northern Africa, and on the Karoo Ground to the 

 North-East of the Cape of Good Hope. By William 

 NicoL, Esq. Communicated by the Author.* 



At a late meeting of the Wernerian Society, Professor Jame- 

 son requested me to examine the structure of some fossil woods 

 which had been found by Mr Cunningham in the island of Mull, 

 and also of some specimens from Egypt, Nubia, and Southern 

 Africa. Having finished the examination, I shall now, in a 

 very few words, lay the result before the Society. 



I. Fossil Dicotyledonous Wood found in the Island of Mull by 

 Mr H. H. Cunningham. 



Mr Cunningham, in his account of the Geology of Mull, read 

 before this Society, states that the fossil woods from that island 

 were found on the beach, about two miles to the westward 

 of Tobermory, and that they had proceeded from the trap- 

 rock, which occupies a considerable extent of coast. The spe- 

 cimens, from the whitening of their surfaces, would seem to have 

 long been exposed to the action of the weather, but they shew 

 no great signs of having been worn by attrition. Some of the 

 masses were six or eight inches in diameter. They were of a 

 greyish colour on the surface, but when recently broken, the 

 fracture surface is greyish black. The cross fracture is in some 

 parts conchoidal, in other parts uneven, and the longitudinal 

 fracture in some parts presents an obscure fibrous structure. 

 All the specimens afford sparks with steel, and are traversed by 

 veins of quartz, which in drusy cavities is crystallized in the 

 usual forms. Each of the masses has a very contorted appear- 

 ance, and when broken up, it seldom happens that any of the 

 fragments display the slightest trace of a ligneous structure. 

 Some of the fragments, however, split in such a manner as to 

 shew the longitudinal direction, and from some of these I have 

 obtained cross sections, which leave no doubt as to the vegetable 

 origin, the structure resembling that of recent dicotyledons. 



The medullary rays are very similar in number, breadth, and 



• Read before the Wernerian Society, on Saturday, 7th March 1835. 



