Having, in March last, received from Mr. Jukes-Browne, F.G.S., of the Geological Survey, a small carapace of a crab obtained by Mr. J. Scanes, of The School House, Maiden Bradley, from a quarry in the Chert Beds of Baycliffe, near Maiden Bradley, Wilts, I endeavoured to identify it with some species of Cretaceous Necrocarcinus already described, but without success. I am therefore reluctantly compelled to refer it to a new species. The specimen is rather imperfect, which renders the task of determining its characters the more unsatisfactory.