Note by the Author :— My attention has been drawn to certain statements in the above paper which need clarification. These are mainly concerned with correlation and misplaced lines in Fig. 11. None of the fossils of the Cementstone and Lower Reef Series (pp. 176 and 181) is truly diagnostic of the C 1 subzone, and these beds should be ascribed to C 2 ; the possibility of a lower horizon being present is suggested solely on the abundance of Productus aff. mesolobus Phillips, though the species also occurs in C 2 and higher beds. The correct alignment of the Manifold column in Fig. 11 will be made if the whole lower portion (Ca, Cb, Cc and Lower Reef) is moved upwards so that the base of Ca aligns with the base of Pe2. The Manifold Limestones-with-Shales (Cc) should then be aligned with S 1 ; there is no evidence of their extension into S 2 . A black triangle should be added to Cb. In the upper series, the Lower Waterhouses Limestone (Da) and the Warslow Limestones (Dl) are probably D 1 , and all the beds above, D 2 , including the Apestor Limestone (Dk) and the Upper Waterhouses Limestone (Db); the “ crassiventer ” beds (Dc) are B 2 -P 1a and the Goniatites crenistria band is P 1a . On Fig. 11, Dn should be eliminated, the top of Dc & m raised, and the top of Db & 1 raised slightly. The fauna at Under Wetton Farm (p. 189) is probably low D 2 ; latissimoid gigantoproductids range from D 1 , though the true Gigantoproductus