140 CLASSIFIED KEY TO THE INDEX. 
( )rdovician — Continued. 
New England and New York I j 
Ohi< > Valley region 1 
Rocky Mountain region 1 
Southwestern region 1 
Oregon 1 
Paleogeography 1 
Paleontology 1 
Cambrian 1 
Carboniferous 1 
Cretaceous 1 
Devonian ] 
Jurassic 1 
Ordovician I 
Quaternary ] 
Silurian 
Tertiary 
Triassic 
In vert el irate 
Vertebrate : 
Paleobotany ' ( : 
General : ij 
Genera and species described ' ij 
Panama : I; 
Pennsylvania 
Petrology 
Alaska i : 
A rizona (! 
California 
Canada 
Cob >rado 
Greenland 
Guatemala 
1 [awaiian Islands 
Idaho 
Iowa 
Maryland 
Massachusetts 
Mexico , .. 
Michigan 
Minnesota 
Montana. 
Nevada 
New Hampshire 
New York 
North Carolina. 
Oklahoma 
( >rogon 
Philippine Islands 
South Dakota 
Texas 
Vermont 
Virginia 
