weeks.] CLASSIFIED KEY TO THE INDEX. 19 
Silurian — Continued. Page. 
Great Lakes region 140 
Mississippi Valley 140 
Rocky Mountain region 140 
Sierra Nevada and Pacific Coast region 140 
South Carolina 140 
South Dakota 140 
Tennessee 140 
Tertiary 140 
Canada 140 
Atlantic Coastal Plain 140 
Mississippi Valley 140 
Cuba 140 
Gulf States 140 
Rocky Mountain region 140 
Sierra Nevada and Pacific Coast region 141 
Miscellaneous 141 
Texas 141 
Utah 141 
Vermont 141 
Virginia 141 
Washington 141 
West Virginia 141 
Wisconsin 141 
Wyoming 141 
