402 
and all the other different species of fossil wood, are the appearance 
of oval or circular spots, from the size of a crow-quill to that of a 
goose-quill, filled with a substance generally of a more crystalline 
appearance, and of a different colour from the ground. The sub- 
stances with which these spots are filled, are sometimes evidently 
calcedonic ; sometimes they resemble cornelian ; and sometimes they 
are complete onachyne agate. The margins of these spots are, com- 
monly, well defined, by a circular or oval line ; in some instances 
this line is hardly perceivable, but in others it is so thick, that being 
continued through the substance of the stone, it describes a perfect 
tubule. In the centre of these spots may be mostly discovered 
starred bodies, differing in colour from the rest of the spot : the 
stars varying in the number of their rays ; some having only four, 
whilst others have five, six, seven, and even eight rays. These stel- 
lated bodies pass through the substance of the stone, so that the 
same star will be seen on the upper as on the under side. The 
variegated surfaces of these stones give them a very curious appear- 
ance : the spots, which are of various colours, red, brown, bluish 
white, &c. are generally quite distinguishable from the ground; 
whilst the central star is also, frequently, plainly distinguishable, 
from its differing again from the colour of the spot Avhich surrounds 
it. Thus a most pleasing mottled surface is formed, such as cannot 
be described, and such as cannot well be copied by art. 
No inquiries which have been made, respecting these stellated 
substances, have as yet terminated satisfactorily. Mr. Walch ob- 
serves, that, in some of these stones, their ligneous origin is ren- 
dered indubitable ; the fibres of the wood being discoverable in the 
transverse, as well as in the longitudinal section of the fibres ; whilst 
in others, he allows it is by no means evident. But, as he remarks, 
the grand difficulty exists in determining the nature of those sub- 
stances which assume this stellated form, and which possess colours 
so various, and so different from those of the other parts of the 
