115 
bituminous properties was derived, were clearly to be seen. 
None of these minute bodies have been discovered in 
anthracite. 
Mr. Boyd Dawkins, F.R.S., then called the attention of 
the Society to a series of fossils on the table in which the 
original matter of the hard parts of the living creature had 
been more or less removed, and replaced by various minerals 
which happened to be in solution in the matrix in which 
they were imbedded. Thus the Trigonia Moretonis of the 
Stonesfield slate was proved to be a mere cast in calcite of 
the space once occupied by the shell of the creature. The 
calcification of the ligament in Cypricardia rostrata and 
Cardium Stricklandi from the great oolite of Enslow 
Bridge (Oxon), and its identity of structure with the valves, 
showed also that the whole of the original hard parts had 
disappeared before their replacement by calcite. The same 
fact was shown to hold good in the case of the corals, which 
only show organic structure on the outside of the fossil. In 
some cases, however, the structure of the outer surface has 
been carried inwards by the petrifying material, as in a case of 
Nuceolites dvmidiatus from the coral rag, in which the 
ambulacral pores and the shape of the angular plates com- 
posing the test were carried inwards to the centre of the 
calcareous spar which now fills the space occupied by the 
soft parts. Other specimens showed that the calcareous 
shell had been replaced by sulphide of iron, phosphate 
of lime, sulphate of baryta, or by silica. The hard parts 
of the vertebrata are better preserved in their original 
condition than fossil shells, from the insolubility of the phos- 
phate of lime in the bones and teeth, 
