In a paper, “On the Geology of the South Coast of England,” published in the Transactions of the Geological Society, vol. i., 2nd ser., pl. iii., fig. 2, p. 42, Sir H. de la Beche has figured a crustacean from the Greensand of Lyme Regis, to which he has not applied any name, or given any other description than that it is “the back of a singular fossil crab.” The specimen is, imperfect, and not very accurately drawn; but Prof. Bell, in his monograph, published by the Palæontographical Society (1862), expresses his opinion that it is an “unmistakeable figure” of Necrocarcinus tricarinatus.