PALEOBOTANY 
587 
problem of their distribution in geologic time is one of 
absorbing interest and importance. The following table 
indicates the known distribution of the various plant 
groups from the earliest geologic time to the present. 
TABLE VII. DISTRIBUTION OF PLANTS IN GEOLOGIC TIME I 
Subdivision, class, 
Division ^,^1. 
Range 
Common 
name or 
VI UIUC1 
example 
I 
1 
Dicotyledones 
Comanchean to present 
Oaks 
O 
"3} 
Monocotyledones 
Comanchean to present 
Grasses 
[ Spermato- 
1 
<j 
IV. v phyta 
( Cycadophyta 
1 
Gnetales 
(Fossil record scant) 
Ephedra 
1 
Coniferales 
Permian to present 
Pines 
% 
Ginkgoales 
Permian to present 
Ginkgo 

Cordaitales 
Devonian to Permian 
Cordaites 
! 
Cycadales 
Permian to present 
Cycads 

Cycadofilicales 
Devonian to Jurassic 
Neuropteris 
Lycopodiales 
Devonian to present 
Club mosses 
[ Lepidophyta 
Equisitales 
Devonian to present 
Horsetails 
III. S Calamophyta 
Sphenophyllales 
Devonian to Permian 
S p h e n o - 
( Pteridophyta 
phyllum 
Filicales 
Devonian to present 
Ferns 
II. Bryophyta 
Musci 
Hepaticas 
Tertiary to present 
Tertiary to present 
Mosses 
Liverworts 
Fungi 
Silurian to present 
Fungi 
Algae 
Pre-Cambrian to present 
Seaweeds 
I. Thallophyta 
Diatomeae 
Jurassic to present 
Diatoms 
Schizophyta 
Pennsylvanian to present 
Bacteria 
Myxomycetae 
(Fossil record lacking) 
Slime-molds 
Modified from Shimer. 
512. Gaps in the Fossil Record. In the Origin of 
Species Darwin called attention to the paltry display of 
fossils in our museums, as evidence of how little we really 
know of the plant and animal life of past ages. "The 
