336 Mr Nicol 0)1 the Structure c>/' Fossil IVoodd: 



extent, to those in some of the recent species of Acer. The ves- 

 sels are numerous, and in general very much compressed, owing 

 to the derangement the wood has undergone, either before or 

 during the petrifactive process ; but in some parts they bear the 

 usual circular or elliptical form of most dicotyledonous woods. 

 The cellular structure, which must have constituted but a very 

 small part of the whole, on account of the number and conti- 

 guity of the vessels, is so much obscured, as not to be seen. 

 All the sections where the vascular structure is seen, present well 

 defined annual layers, varying in breadth from a tenth to an 

 eighth of an inch. 



All these fossil woods of Mull, collected by Mr Cunningham, 

 belong to the same species, and are the only specimens I have hi- 

 therto seen of the dicotyledonous series from rocks of the second- 

 ary class. , 



II. Fossil Woods found iti Egypt and Nubia by the Rev. Verb 

 Monro. 



The Egyptian and Nubian specimens which have been put in- 

 to my hands, are seven in number. They are all of the sili- 

 ceous kind. Two of them can merely be inferred to have had a 

 vegetable origin from their external appearance, for internally 

 they are formed of yellow jasper, without organic structure. A 

 third specimen may have been wood, but it presents nothing but 

 a congeries of fibrous substances, so slightly cohering, that it is 

 impossible to decypher it by slicing it in the usual way. The 

 remaining four are undoubtedly of vegetable origin. One of 

 these is a conifera, the others are dicotyledons. The mass 

 containing the conifera is an aggregate, consisting of fragments of 

 the fossil wood, and grains of quartz, united by a cement, con- 

 sisting chiefly of carbonate of lime, with a little iron and clay. 

 The fragments of wood are of an elongated form, and of various 

 dimensions, the largest being little more than an inch in length. 

 They are lying in different positions intermixed with the grains 

 of quartz, and the aggregate is in some part cavernous. Exter- 

 nally, the woody portions are of a greyish-black, but internally, 

 the colour at least of one of the specimens was hair-brown. By 

 reflected light, the hair brown-fragment shews no appearance of 

 organization even when polished ; but when a transverse section 



