In the Geological Magazine for November last (Decade III. Vol. IV. p. 481, Pl. XIII.) I gave a brief description of a new species of Eurypterus from the Lower Carboniferous Shales, Eskdale, Scotland, which I named Eurypterus scabrosus.I referred to other Carboniferous forms, and briefly mentioned one from the Lower productive Coal-measures, Darlington, Pennsylvania, U.S.A., figured as a woodcut only in the American Phil. Soc. Proc. vol. xix. p. 152, 1881.