54 
cabinet of Ingham Forster, Esq. but am unable to determine whether 
it is not the same fossil with the last described, differing only in the 
size of its stars. 
Madrepora arachnoides, with close, smooth, and delicate stars, the 
rays of which are slightly waved. This fossil is figured with tolerable 
accuracy both by Scheuchzer* and by Volkmann.-j- It appears to be 
this fossil to which the remarks of Langius most properly apply, where 
he observes, “ aliquando stellarum loco rosas exhibent, & tunc rhoditce, 
Oder rosenstein, vocantur ; aliquando cometes, prae se ferunt & cometita, 
vel cometstein nuncupantur.'’^ These remarks of Langius are employed 
in illustration of a fossil coral, represented Tab. XX. of the above work, 
and named by him, astroites stellis maximis; which figure has been 
selected by Gmelin, as illustrative of the madrepora vermicularis, but 
which is undoubtedly in more exact agreement with the coral which is 
the subject of our present examination. 
In the specimen, Plate VI. Fig, 4, from Chatelor, the particular 
characters of this coral are observable. The slightly waving rays 
which proceed regularly from the centre, and are diffused over the 
flat surface, yield some faint resemblance to a flower ; and from the 
elongation of these rays, as may be seen in the magnified star, 
Plate VI. Fig. 6, the idea has originated of their resemblance to the 
web of a spider, or to the streaming tail of a comet. From these 
different appearances, which are also' very strongly marked on the two 
opposite sides of a specimen before me, have proceeded the names which 
this fossil has acquired of rosenstem and cometstein. A considerable tract 
of road from Bath, through Chippenham and Malmsbury, in Wiltshire, 
is kept up by a coarse, light, brown lime-stone, formed by this 
madrepore. 
Madrepora vermicularis, the stars of which are formed of unequal, 
smooth, waved radii, several of which are bifurcated, is certainly much 
* Lithographia Helvetica. Fig. 54. f Silesia Subterranea. Tab. XVIII. Fig. 11. 
% Historia Lapidum Figuratorum Helvetiae, &c. P. 60. 
