3^6 
which has been just described, from its possessing hardly any 
vacuities. The texture of the wood is very evident, and even the 
knots of the wood are frequently perceptible : but, as in the Bovey- 
coal, so in this fossil, the woody fibres are distorted in various direc- 
tions, in such a manner as could not have taken place, if they had 
not been in some degree softened. The calcareous spar, which per- 
meates the wood through every part, marks it in many places with 
streaks of a beautiful pearly white, formed by the deposition of the 
spar from its infiltrated solution ; and when this happens to have 
been the case in a cavity rather larger than the others, such an 
arrangement of the particles of the carbonate of lime will sometimes 
take place, as is observed in cavities large enough to allow of the 
formation of stalactites, and the cavity will be found to be filled with 
striated or fibrous carbonates, or alabaster. Thus, under one or the 
other of these forms, will the carbonate of lime be found to fill 
every cavity and rift in the wood which had been produced by the 
mechanical action of the water in which it had lain, or by subsequent 
shrinking of the wood. 
The calcareous fossil wood which is found in the neighbourhood 
of Bath, and of which a specimen is depicted in Plate VIII. Fig. 4, 
resembles very much in colour that of Charmouth ; but is harder, 
and retains, still more perfectly, the form of the wood. In the par- 
ticular specimen, described in the Plate, the spar so penetrates the 
mass, as to accompany the fibres, in all their directions, in threads, 
so minute as to be discovered, in many parts, only by the aid of a 
lens, of no small power. It is also pervaded through its whole sub- 
stance by a mass of spathose matter, about half an inch in width ; 
and yet the fibres of the wood are nearly as evident, on the polished 
surface, as if they had undergone no change. 
Whilst inquiring into the nature and origin of silicious fossil 
wood, I ventured to attribute its formation to the impregnation of 
wood, chiefly, in different stages of bituminization, with silicious 
