Trias. New Red Sandstone, or Triassic deposits.
Carb. Carboniferous or Coal formation.
Mt. L. Mountain or Carboniferous limestone.
Devon. Devonian or Old Red Sandstone formation.
Sil. Syst. Silurian System, or formation.
§ 2. Relative to Organic Remains.
nat. Natural size.
× Magnified in diameter: e.g. × 8, magnified eight diameters, &c.
× × Highly magnified; the degree not accurately determined.
inv. Invisible to the naked eye.