66 



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 an 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, result- 

 ing 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 x 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 re- 

 quired lapidific power, and which it has exerted during its interposi- 

 tion between these detached fragments. 



A piece of this marble was suspended in a glass vessel, containing 



