Article: Taxonomy and opercular function of the Jurassic alga Stichoporella

Stichoporella stutterdi (Carruthers) Edwards is shown to differ from S. cylindrica (Lignier) Pia in the form of the distinctive opercula which terminated the side-branches in the reproductive stage of development; previous accounts of the difference were based on damaged examples. The opercula of S. stutterdi support the suggestion of Fily and Rioult (1976) based on S. cylindrica, as to their being formed immediately prior to cyst formation, and being shed to allow cyst-dispersal. The microstructure of the opercula in S. stutterdi is described. S. cylindrica is recorded only from the Middle Jurassic of northern France; S. stutterdi has a more northerly area of occurrence, overlapping with S. cylindrica in France but also occurring in the English midlands.