636 
Proceedings of the Royal Society 
That mineral speaks for itself. As to the others, I found the 
blue-black in distant octahedral crystals : they are spinel , possibly 
picotite , though I have not determined the presence of chromium. 
The grey-yellow granules are generally rounded on the angles, as is 
so frequently the case with minerals imbedded in a limestone which 
has been subjected to the extreme energy of metamorphism. But 
this substance I have also got in crystals. These are of a pale 
fawn colour, identical with that of danburite; but the form of the 
crystal is that of chonclrodite. The presence of fluorine I have not 
yet determined; and as there is a form of sahlite almost indis- 
tinguishable from that of chondrodite, I will not say that these 
crystals may not be this mineral, which is the common ingredient 
of such marbles. The white matrix (soluble in the rain-water) 
afforded me, on analysis — 
Carbonate of lime, 
46-307 
j) 
magnesia, . 
37-632 
55 
iron, . 
1-022 
55 
manganese, . 
•368 
Insoluble (chondrodite 1), 
15T08 
100-437 
and is thus a ferruginous dolomite. 
Such are the chemical and mineralogical materials of which this 
fabric is composed. The fashion and mode of arrangement of these 
materials I leave others to unfold; inasmuch as they appear to 
me not to have been subject to the laws which govern molecular 
arrangement in crystals; and that hence, the thing, as a whole, is 
not a mineral body, but an organism. 
When it shall have been said, in leaving the question at this 
stage, — standing aside to give the histologists and palaeontologists 
their innings at the describing of the thing , — that I am merely 
evading a duty, self-imposed in virtue of the foregoing expression of 
opinion, I shall be prepared to state the grounds upon which I hold 
that its structure cannot fall to be considered under crystallipolar 
arrangement. Meanwhile, I think it well to leave that which is 
to be seen to those who can describe the complexities of flowing 
lines and curvilinear outlines, so much better than one who deals 
with straight lines and angular inclinations. 
