A study of well preserved fossil cuticle material of Hirmeriella muensteri from the Liassic of Franconia (Germany) was carried out using transmission electron microscopy (TEM), as well as scanning electron microscopy (SEM) and light microscopy (LM). The ultrastructure of normal epidermal cells is described as well as that of the stomata with a differentiation into guard and subsidiary cells. The ultrastructural details allow not only a discussion on the taxonomic position of the species, but also on the structure/function relationships, xeromorphism and the ability of the guard cells, and to a lesser degree of the subsidiary cells, to change in shape and volume for opening and closing.