I have again been privileged by Professor A. Geikie, Director-General of the Geological Survey of Great Britain and Ireland, in being allowed to bring before this Society the results of a further study of the Crustacea and Arachnida obtained by the Geological Survey from the Lower Carboniferous rocks of the Scottish Border. Since my former papers on those subjects were read, a considerable amount of fresh material has come to light, which has allowed of many species, which were formerly represented by fragmentary specimens, to be more fully described, and several altogether new to science to be added to our former list.