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obtained from Hudson’s Bay, pretty large specimens of this coral very 
much changed by the decomposition of their surface, either by long- 
exposure to the action of water or of air, after having lost their inha- 
bitants, or by having been buried in the earth. The change, in such 
specimens as I have broken, did not, however, appear to have ex- 
tended to such a depth as to have allowed the classing them amongst 
the fossil corals. Boetius de Boot gives the representation of a spe- 
cimen evidently bearing the figure of this coral, but which from the 
form and size, which it appears to have derived from the labours of 
the artist, and from its having been considered by the author as 
deserving to be ranked among the gems fit to be worn as ornaments, 
there is good reason for believing it had undergone an impregnation 
with silex.* 
Neither madrepora sinuosa, nor m. maandrites appear to have been 
described as having been seen in a mineralized state. A specimen of 
areola, now before me, the history of which is unknown, bears such 
marks as give considerable reason for believing it may with propriety 
be considered as a fossil. Its inferior surface has evidently much suf- 
fered from decomposition, the effects of which are still more plainly 
observable on the superior surface, and particularly on the feather-like 
lamellae, which have acquired an opaque whiteness, and are nearly 
covered with a whitish-grey calcareous matter, with which the inter- 
posed cavities are nearly filled. Although I entertain but little doubt of 
this being a fossil coral, yet, as it is not incontestibly so, I have not 
ventured to introduce its representation. 
I do not recollect to have seen either madrepora abdita, m. phrpgia, 
m. dcedalea, m. cerebrum, orm.gyrosa, in a mineralized state ; and am by 
no means sufficiently acquainted with the particular forms of madre- 
pora repanda, m. ambigua, m. clivosa, m. imoluta, m. implicata, or of 
m. cochlea, to be able to speak with respect to their existence as fossils. 
* Gemmarum et Lapidum Historia. Liber II. Cap. CXLV. P. 297. 
