POSSIL CEPHALOPODS. 301 



My readers are fully aware that those parts most 

 precious to the geologist — viz. those which resisted 

 decay because of their hardness and earthy composi- 

 tion, such as shells, corals, spines, tests, etc. — do not 



Fig. 299. — The Pearly Nautilus, with animal in last chamber ; (recent, chambers 

 in section to show structure). — /, siphuncle ; x y, chambers ; z, body-chamber. 



necessarily represent the most important parts of the 

 animal economy. The geologist has still to be thank- 

 ful for those shreds of evidence which not long since 

 were regarded by conchologists and others as the sole 



