121 
ing those who have regarded them as the petrified remains of terrestrial 
mushrooms. 
The shape of these bodies approaches so nearly to that of a mush- 
room, as to fully authorize the name by which they have been generally 
distinguished by oryctologists. This resemblance has, however, led to 
an erroneous mode of describing them ; every author having, as 
Mr. Walch has done, in his description of these fossils, considered the 
convex part as the superior, and the concave as the inferior, as is the case 
with terrestrial fungi. But analogy teaches us that these bodies grew in 
a contrary manner ; the pedicle, by which they were attached to other 
bodies, proceeding from the centre of their convex part, and their 
concavity being, of course, on their superior part. 
The fungiform fossil, Plate VIII. Fig. 5, has a considerable conca- 
vity on its superior part, and a corresponding convexity on its inferior 
part. It is formed by tolerably distinct radiating lamellae, or plicae, 
which, passing from the centre to the circumference, are frequently 
seen to divide, and then again unite ; thus forming a species of inos- 
culation. This structure is here shewn on its inferior surface, where the 
laminae may be seen concentrating themselves in that part which had 
been continuous with the pedicle. 
On comparing the radiating lamellae, of which this fossil is com- 
posed, with those of the alcyonium depicted Plate XI. Fig. 3, this 
similarity will be directly perceived. In both these fossils it will be seen 
that the lamellae frequently unite, as it were, by inosculation, and 
are but rarely connected by interposed transverse processes. In this 
fungiform specimen, this peculiarity of structure, shewn on its infe- 
rior surface, is equally evident on its upper surface, which, however, 
is not here represented ; since the genei'al idea of the appearance yielded 
by the concavity of its superior surface will be sufficiently obtained by 
the view given of the next fossil. 
A very slight examination of the upper surface of this fossil alcyo- 
nium, Plate XI, Fig. 7, will be sufficient to enable you to perceive 
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