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In fineness of grain and in susceptibility of polish it appears to equal 
any marble. From this circumstance, and from the considerable dif- 
ference in the colour of the madrepore and of its matrix, the structure 
of the former becomes very conspicuous, and the astonishing labours 
of its original inhabitant are very easily traced. In one part, the 
converging perpendicular plates, displayed by a horizontal section of 
the madrepore, are discovered ; whilst, in another part, a longitudinal 
section has not only shewn numerous horizontal plates ; but also yields 
a fair view of the beautiful reticular texture of the coral, resulting 
from the frequent intersections of the perpendicular by the transverse 
lamellae. 
The very considerable difference of colour in the ground of this 
marble and in the animal part is particularly deserving of attention. 
As in the former specimen the regular diffusion of colour through 
the whole mass appeared to authorize the conjecture that the colouring 
matter was introduced previous to the coral having undergone its 
lapideous change; so here, the exclusion of the blackening particles 
from the coralline part of the marble seems to warrant the supposition 
that the coral had acquired a stony impregnation previously to its 
having become imbedded in the including mass of calcareous matter. 
Thus two distinct lapidific processes, occurring, perhaps, at the distance 
of many ages, may have been employed in forming the marble of which 
we are now treating. Any difficulties which appear to be in the way 
of this supposition will diminish, when it is considered, that in several 
marbles, indeed in all the breccia marbles, this two-fold lapideous im- 
pregnation must necessarily be admitted. These are composed of frag- 
ments of various marbles, which, after having been formed in perfect 
strata, have been broken into small pieces, and have then become 
agglutinated into a compact mass, by the medium of a fluid, which, 
from its saturation with the carbonate of lime, has possessed the required 
lapidific power, and which it has exerted during its interposition between 
these detached fragments. 
A piece of this marble was suspended in a glass vessel, containing 
