In continuation of the descriptions of the fossils from the Menevian group which have at different times appeared in the ‘Journal’ of the Geological Society, I propose now to add those forms, which though frequently referred to in our communications, have hitherto remained undescribed. So far as present researches have gone, these will also complete the fauna of the Menevian group as exhibited in Wales. The additions made to the fauna of the Cambrian rocks (Longmynd and Menevian groups) by these researches, include no less than fifty-two new species, belonging to twenty-three genera. The following Table shows to what orders these belong, and in what proportion they occur in these early rocks. If we now add to these the annelids which had been previously discovered in these rocks we have at least seven orders represented in this fauna, the earliest at present known. These same groups are also more or less present and tend to characterize these early deposits wherever found: but no country has up to the present time produced a more varied fauna or a greater richness in types than England. Scandinavia has a larger number of species, but not so many groups. On referring to the Tables in M. Barrande's excellent work on Trilobites, lately published, we find the following results given, with reference to those forms discovered in the lowest or Paradoxides zones in different parts of the world. The groups are those given by him in the Tables. From this Table it will be observed