Chapter 9

The Lower Silurian period--The Silurian rocks generally--Limits of Lower and Upper Silurian--General succession, subdivisions, and characters of the Lower Silurian rocks of Wales--General succession, subdivisions, and characters of the Lower Silurian rocks of the North American continent--Life of the period--Fucoids--Protozoa--Graptolites--Structure of Graptolites--Corals--General structure of Corals--Crinoids-- Cystideans--General characters of Cystideans--Annelides-- Crustaceans--Polyzoa--Brachiopods--Bivalve and Univalve Molluscs--Chambered Cephalopods--General characters of the Cephalopoda--Conodonts.