4 
[II. 
(b) Fossil: — 
Quaternary... 
Oainozoic ... 
Pleistocene... 
Tertiary 
Pliocene 
Miocene 
Oligocene .... 
Eocene ... 
Cretaceous ... 
Jurassic. 
Triassic and Liassic 
Carboniferous 
Devonian 
Silurian 
Ordovician ... 
Cambrian 
Systematic Index = 2231 : — 
Gastropoda 
Amphineura 
Aplacophora ... ... ... ... ... 
Polyplacophora 
Pro3obranchia 
Opisthobranchia, including Pteropoda and Heteropoda.. 
Pulmonata ... 
Scaphopoda ... 
Pelecypoda or Lamellibranchia 
Cephalopoda ... 
PAGE 
>29 
>30 
. >30 
. I 
J 
. 43 
. 44 
. 50 
. 50 
. 57 
