99 
TABS CCE. 
SILEX  quartzum. 
Diy. 2. Imitative. 
Turs might be called a Jasperine or Porcelain Flint, and 
is extremely curious, as having taken place of a shell much 
resembling Venus Islandica, and seems merely to differ in 
being deeper. This appearance is rarely found, especially in 
the place, as it were, of the shells themselves. 
The top figure shows fragments of an Escallop, looking 
like recent ones, but are of a most compact Silex, semi- 
transparent like the natural shell. 
The lower figure shows a transverse piece, separated at 
the crack, with somewhat dendritical veins, giving the ap- 
pearance of China. It has also the cast of other shells that 
were involved in the same catastrophe. The Rev. Dr. Becke 
was so good as to favour us with this curious specimen, 
which was found at Little Teignmouth in Devonshire ; and 
the Rey. Dr. Sutton has favoured me with a shell, probably 
of the same species, from Elmsett in Suffolk, but little 
changed, being nearly like such as may be found exposed, 
and dead, on the coast. It has some fragments of Sertu- 
laria with Lime and Gravel about it. I have some of the 
same, which I found at Sydenham when the canal was 
digging there in the year 1805, in a marly Septarium. So 
we may trace the same shell at very different places; which 
will not only be a help in geology, but will show at one 
view the varieties to which Flint is liable, and not only 
that it may be capable of taking casts or impressions, but 
be in different states during that operation. In this instance 
it seems to have been considerably diluted, as the dendrites. 
(if I may so call the red lines) are much attenuated. 
H 2 
