the central part being filled by the same kind of substance disposed 
somewhat in a retiform manner, projecting a little beyond the la- 
mellated exterior part. This peculiar structure presents to the eye a 
floscular appearance, very difficult to describe, but which is very 
faithfully represented by the magnified figure, Plate XII. Fig. 6, a. 
By the aid of the lens it is also discovered, that the greater part of 
the ground on which these bodies are disposed, is adorned by slightly 
undulating, faint, and minute striae, which, in some places, appear to 
unite with, or even proceed from, the plates of which those bodies are 
formed. So numerous are these waving striae, and so many are the 
slight traces of them, as to render it quite fair to suppose that they 
were originally disposed over the whole surface. Mr. Walch describes 
this fossil as a tubercular astroites, on a ground marked with deli- 
cate striae; the projecting parts, he thinks, may have been casts of a 
columnar astroites, and now reduced to a mammillary form.* 
In Faujas St. Fond's elegant work on the natural history of the 
Mountain of St. Petre, in which many of the riches of that immense 
mine of fossil are displayed, two specimens are depicted, which bear 
considerable resemblance to the fossil which now demands our atten- 
tion. 
The one figured by Faujas St. Fond, which, in its general appear- 
ance, approaches the nearest to our fossil, is to he found Planche 
XLI. Fig. 1, a. and Fig. 1, b.-j- This specimen differs from our fossil 
in two respects ; First, the rose-like protuberance are placed with 
a great deal of regularity, upon lines which appear to form concen- 
tric circles round the centre, whilst in those of the fossil figured in this 
work they are not disposed in any regular order. Secondly, the ground 
of the fossil described by Faujas St. Fond is very finely granulated; 
whilst in the fossil here figured, the rose-like stars are placed on a 
* Recueil des Monumens, &c. Tome III. Page 163. 
t Histoire Naturelle de la Montague de Saint Pierre de Maestricht, Page 210. 
