[ 39 8 ] 
with a regular jointed conic Body, called by Litho- 
logift the Alveolus of the Belemnites ; which, tho 
conftantly regular and jointed, is neverthekfs found 
compofed of various mineral or metallic Subdances. 
The Alveolus above-mentioned, tho not fully 
proved fuch, yet feems, by the Aflent of mod of 
the prefent Naturalids, to be a Body of marine 
Origin 5 a Shell the nighed related to the Nautilus 
Kind: It is concamerated, and even in fome is difeo- 
ver'd another great Chara&eridic of the Nautilus 
Kind, I mean the Gut or Siphunculus . Therefore, 
taking this Body for granted to be' of marine Ori- 
gin (for what Reafons, or of what Kind, is not my 
prefent intended Subject to prove) it remains to 
difeufs, Whether this Body became accidentally lodged 
in the Belemnites? or, Whether the Belemnites 
itfelf is alfo of marine Origin, and a Part dependent 
on its Alveolus ? 
Various have been the Opinions of Lithologifts 
concerning the Origin of the Belemnites 5 fome have 
even alfertcd them of the Vegetable Kingdom ; others, 
that they are Teeth or Horns of Fifh, Appendages 
of Shells, Bodies cad in Shells of the Tuhuli Kind, 
or the very Shells themfelves, Spines of Echini , or 
a kind of ftrait Nautilus . The three lad Opinions 
are what I (hall drive to confute, as they feem fome- 
what probable, and are now the mod prevailing; 
and prove the Belemnites to be a natural Foffil or 
Lapis fui generis. I defire no Recourfe to the Sub- 
terfuges uled by others, but hope, Sir, you will 
agree with me in the Axiom, that all Belemnites 
are of one and the fame Origin, 
That 
