"The trends in variation of the different species groups of Lenticulina from the Lias are shown. The plexus of evolving forms is discussed and the stratigraphical significance of the various species groups is given. The gradation from the coiled lenticuline to an uncoiled at flabelline stage is demonstrated. The evolutionary, biological and stratigraphical aspects are stressed rather than the purely taxonomic approach. Some forms described by other authors are discussed, but a complete synonymy is not attempted."