a1 24 Monmouth Street, Topsham, Exeter EX3 OAJ, U.K.
a2 Botanical Museum, University of Oslo, Trondheimsveien 23 B, N-0562 Oslo, 5, Norway
Pannaria is shown to include species whose thallus ranges from the almost homoiomerous to the fully differentiated heteromerous state. A new species of Pannaria is described, P. santessonii, with a thallus closely resembling that characteristic of the Collemataceae. Lepidocollema carassense Vainio and Lepidoleptogium montaguei A. L. Sm., the type species of these respective genera, have beenfound to have a similar type of thallus. Further study of the relationship between thesegenera is needed.
(Accepted March 28 1986)