4 
(b) Fossil — continued : — 
Palaeozoic 
Carboniferous 
Devonian 
Silurian 
Ordovician 
Cambrian ... 
HI. Systematic Index = 2231 : — 
PAGE 
>27 
Gastropoda 
Amphineura 
Aplacophora 
Polyplacopliora 
Prosobranchia 
Opisthobranchia, including* Pteropoda and Heteropoda 
Pulmonata ... ... 
>27 
28 
40 
41 
Scaphopoda ... 
45 
Pelecypoda or Lamellibranchia 
Cephalopoda 
45 
53 
k. 
