132 
which bears, externally, the ridges corresponding with the conca- 
merated structure of the shell. 
I have never yet seen any other part of the belemnite in a pyritous 
state, except the concamerated part. In one specimen, the spathose 
part of the belemnite is imbedded in a mass of pyrites, with a pyritified 
Cornu ammonis ; but it does not appear to have undergone any change, 
by metallic impregnation. 
The matrix, in which these fossils are found, is generally calcareous ; 
sometimes chalk, but most commonly limestone. Some of the marbles 
of Altdorff are chiefly formed of these bodies, and are thereby rendered 
of a dark brown colour. In a specimen before me, formerly in the 
Leverian Museum, the marble appears to be chiefly composed of these 
bodies, mixed with a few other marine remains ; and in one part of the 
polished marble, a section is displayed of the concamerated part, show- 
ing distinctly the several chambers and partitions. Sometimes, but 
much more rarely, the belemnite is found transfixed in common flint, a 
specimen of which is figured Plate IX. Fig. 1. 
That these animals must have existed in very considerable numbers, 
in the former world, is very reasonable to conclude, from the very wide 
extent over which their mineralized remains are now found. Lhwydd 
appears to think, that in England they are so abundant, that Cam- 
bridgeshire only is destitute of them. Besides the proof of their general 
diffusion, from the various parts of the world from which those have 
been obtained which we find in the cabinets of the curious, we have 
particular descriptions, in the writings of different or y otologists, of the 
several fossils of this description which have been found in Saxony, Swa- 
bia, Franconia, Brunswic, Salzthal, Goslar, Calenberg, Hildersheim, 
Potsdam, Niendorp, Lubec, Angerbourg, Francfort, Switzerland, Spain, 
France, and Great Britain. 
