PLATE 1. 
constituent substance is siliceous: the colour, externally, 
yellowish brown; internally, blackish grey, blotched and 
radiated with brown and white. , Fracture somewhat slaty ; 
fragments sharp (3. Kirwan.) ; texture * fibrous. The 
dark parts opaque (1. Kirwan); the white semitransparent 
(2. Kirwan); the latter much finer in texture than the 
former, with a structure less evidently lignious — The 
lighter parts appear to pass into calcedony. 
' The face of the specimen exhibits a transverse section of 
the original trunk : its figure triangular ; two-thirds of the 
circle it would otherwise have formed, having been broken 
off in the sawing — The annual rings and radial insertions 
are beautifully and distinctly marked ; more so than in any 
other fossil of this kind which has yet come under my 
examination. 
All the petrified wood hitherto collected in this county, 
appears to have been oak, and the constituent matter 
constantly the same as that of the piece now figured 
Holzstein or Woodstone of the German mineralogists. 
(Kirwan. Min. E. 2d. 315.) 
* Should not some distinction be observed between the texture and the 
fracture of a fossil ? Mineralogists of the Geiman school seem to consider 
the terms as synonymous. 
