Chapter 7

The Laurentian and Huronian periods--General nature, divisions, and geographical distribution of the Laurentian deposits--Lower and Upper Laurentian--Reasons for believing that the Laurentian rocks are not azoic based upon their containing limestones, beds of oxide of iron, and graphite--The characters, chemical composition, and minute structure of _Eozoön Canadense_--Comparison of _Eozoön_ with existing Foraminifera--_Archoeosphoerinoe_--Huronian formation--Nature and distribution of Huronian deposits--Organic remains of the Huronian--Literature.