Originally issued between 1887 and 1907, this monograph by Sydney Savory Buckman (1860–1929) remains the most comprehensive record of British Aalenian to Lower Bajocian ammonites. Reissued here in two volumes, it features superb, accurately drawn illustrations, with some photography. Buckman's early ideas on biochronological subdivision and zonal succession are presented along with refinements in the supplement based on later research. Exhaustive descriptions of numerous morphospecies are given, many prepared when Buckman resided in Dorset and was thoroughly familiar with the local succession. He observed that it was possible to further subdivide strata beyond the zonal scheme of the day. This work laid the foundations for further writings on natural evolutionary classification and time-rock duality. Unfortunately, the monograph was discontinued before the remaining part concerning the Lower to Upper Bajocian and Lower Bathonian was completed. Nevertheless, it remains essential reading for establishing an understanding of Inferior Oolite ammonites.