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I am unacquainted with the place where these fossils are found ; 
but, from the nature of the matrix, suspect it to be Stunsfield, in Ox- 
fordshire. The markings on the stone are so very thin, as to lead to 
the supposition that the fossil body has been removed, and has only 
left its impression and stain on the stone. The stone itself is a lime- 
stone, very full of Oolithes, with shells dispersed through it, exactly 
resembling the Stunsfield stone, in which are found the teeth and 
palates of fish. In another fossil of this kind, the markings vary so 
much from the preceding, as to render it, I think, deserving to be 
regarded as specifically different. 
The wings of butterflies are said to have been found in a mineralized 
state ; but this I very much doubt, suspecting that the opinion has 
been derived from some delusive appearances. 
When you take into consideration the particular characters by which 
the several species of the genus Cancer are marked, and the injuries 
which the fossil animals of this genus have sustained, you will see, I 
trust, the very great difficulty of distinguishing the species even by 
those who possess, what I do not, an intimate knowledge of this 
branch of natural history, and an ample collection of both the recent 
and fossil objects of our inquiry. 
It happens, indeed, very unfortunately, that in the fossil remains, 
traces of the antennae, and the terminations of the hinder feet, are 
hardly ever to be seen. The containing crust of the animal, with 
some portions of its claws, are generally the only parts preserved ; 
but the incisural and dentated markings on the sides and fore part of 
the former, and the terminations of the latter, are very seldom dis- 
coverable. It is only from the size and general forms of this kind of 
fossils, that we can offer any opinion with respect to their species ; 
and, where the approximation of the fossil is, in this respect, near to 
the recent animals, but little prospect of success can exist in attempt- 
ing to make a distinction between them. 
I am entirely unable to say anything with respect to the specific 
