skipper's island papers 335
Lecanora dispersa, which was formerly divided into several
species, also presents, in this habitat, a great range of variation.
A form with large (up to 2 mm. in diameter) pale, crowded
apothecia, with thick, often irregular margins occurs commonly
round the bases of the posts. Elsewhere occur forms with small,
regular apothecia which are sometimes pale, but sometimes a
darker reddish-brown with either a thickish margin (= L. umbrina
(Ehrh.) Massal.) or a thin, disappearing margin (=L. hageni
Ach.). I agree with Laundon (1957) that these forms are not
specifically distinct. That the variation, however, is not wholly
explainable in terms of ecotypes is indicated by the fact that two
or more thalli of different appearance often grow side by side.
Some indication of the lichen zonation on higher posts is
indicated in the table (Fig. 2) giving the approximate percentage
cover of species on the S.W. side of oak posts situated at about
the same level in relation to the tide as the others. The data
represent the averages of figures obtained from two different
posts.
Away from saltings, the commonest lichens growing on wood
(mainly old oak posts) are Lecanora conizaeoides, L. expallens
and Cyphelium inquinans; also recorded have been Psora ostreata
Hoffm. and Buellia myriocarpa (DC.) de Not. var. chloropolia
(Fr.) Krb.
4. Bricks. The only saxicolous lichen community on
Skippers Island is that occupying old bricks deposited on the
sea-walls chiefly on the N.W. side. Here, Catillaria chalybeia,
Rinodina demissa and Lecanora dispersa are usually more or less
are Xanthoria parietina and Candelariella vitellina. It is note-
worthy that all these species are also abundant on wood in a
similar situation.
Taxonomy. The taxonomic nomenclature used is the same as
that used by Duncan (1959).
References
Duncan, U. K. (1959). A guide to the study of lichens. Arbroath.
Laundon, J. R. (1957). The lichen vegetation of Bookham Common.
London Nat., 37: 66-79.
Skippers Island Papers
(4) THE MAMMALS OF SKIPPERS ISLAND
By Alwyne C. Wheeler
This brief account of the mammals of Skippers Island is based
on the notes I have made during a number of visits for the
purpose of catching small mammals with Longworth live traps,
and on casual observation of the larger mammals. I have also