Having described in some detail, the rocks of the Maentwrog, Festiniog, and Dolgelly groups, and given a list of the fossils found in each, I shall now make some general remarks upon the fauna. In Part I. I have mentioned that out of all the numerous Trilobites from the Lower Cambrian rocks, only two genera, Agnostus and Conocoryphe, have been found in higher strata. Strictly speaking, this is only true of Agnostus, which passes unchanged in type from the Menevian to the Caradoc strata. On the contrary, the species of Conocoryphe from the Lower Cambrian rocks are of essentially different type from those that have been placed in that genus from higher beds. The latter have, I believe, been referred to the genus Conocoryphe rather from superficial resemblances than from true affinity.