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parts, the quadrangular spaces mentioned in the preceding fossil, and 
which are, in this fossil, disposed with a considerable degree of regularity. 
This fossil is apparently of a similar substance with the two former, and 
was obtained from Randenberg, near Schafhausen. 
A circumstance, particularly deserving your attention, is observable 
•in the three last fossils. In the first, the perpendicular lamella are 
slightly connected by very few transverse processes, and by still few'er 
ramifications : in the second, the connexion is preserved chiefly by 
anastomosing ramifications of the lamellae ; and in the last, almost 
entirely by transversely disposed processes or filaments. This difference 
IS very obvious ; and if the two fossils. Fig. 1 and Fig. 6, had only been 
obtained, no one would have hesitated to have regarded them as 
distinct species ; but in the structure of the one, Fig. 3, so much of the 
characters of both the former is to be found as necessarily connects 
them together, and shews that they all are referable to the same 
species. 
Hence you may perceive how little can be done, in the present state 
of the science, in forming any useful classification of these fossil animal 
remains ; since more opportunities are necessary to empower any one to 
determine which may be considered as distinct species, and which should 
be regarded merely as varieties. 
The two fossils, which I shall next place before you, will also, I trust, 
serve to shew the difficulties w'hich 1 have just spoken of. These fossils, 
although differing so much in form from the preceding, possess the 
same kinds of structure which were observable in them ; the one being 
characterized by the connexion between their lamellae being kept up 
by inosculation, and the other by the means of interposed transverse 
processes. Whether these two fossils should be considered as of 
the same species with the preceding, 1 will presently endeavour to 
learn. 
These fossils are of that kind which have been generally considered 
as fungites, or petrified sea-mushrooms ; nor have there been want- 
