The above form I found a year or two ago in the Encrinital Limestone forming the upper bed of the Lower Limestone Shales which occur on the south side of Combe Down (overlooking Combe House), near its western extremity. I have also traced it in an outcrop of the same limestone in the plantation on the north side of Kings-weston Down, near its western extremity. At both these localities the fossil is associated with Zaphrentis Phillipsi, a small coral which is characteristic of the bed. Palæacis probably also occurs in the corresponding beds exposed in the Avon section, and elsewhere; but though tolerably abundant, is not likely to be observed, on account of its small size, except where the rock is well weathered. The accompanying are sketches of two specimens from Combe Down which much resemble those figured in the Geol. Report of Illinois (Meek and Worthen), vol. ii. p. 262, plate 19, fig. 1 a, b, c.