144 THE ESSEX NATURALIST
Billericay (1974, PME-B) and St Mary's, Runwell (1974, PME-B); shaded
crevices and base of wall, All Saints' Church, Hutton (1974, PME-B).
B. umbrina (Ach.) Bausch
Scarce on concrete and brick. 51/68, 69.
Top of concrete post, railway station, Billericay (1973, PME-B); vertical
surface of brick railway bridge, near Dunton Hall (1974, PME-B).
Buellia epipolia (Ach.) Mong.
Scarce on concrete, mortar and limestone. 51/69, 79.
Concrete bridge over stream, Hutton (1971, PME-B); limestone grave-
stones and mortar of wall of St Mary's, Runwell (1974, PME-B).
B. canescens (Dicks.) DNot.
Frequent on limestone and sandstone; rare on Ulmus. 51/69, 79.
Limestone gravestones, All Saints', Rettendon (1971, IMH) and St
Mary's, Buttesbury (1971, IMH); vertical surfaces of limestone headstones
in churchyard of All Saints', Hutton (1972, PME-B); sandstone grave-
stones, St Mary's, Little Burstead (1973, IMH); few small thalli on bole
of Ulmus, Stock (1973, IMH) and similarly on stump of hedgerow Ulmus,
by St Mary's, Runwell (1974, PME-B).
B. punctata (Hoffm.) Massal.
Frequent on the boles and lower parts of trunks of Ulmus, Fraxinus and
Salix; rarer on palings and sandstone. 51/68, 69, 79.
Roadside Ulmus, Hutton (1972, PME-B); boles of Fraxinus and Ulmus
in hedgerows, Norsey Farm, Billericay (1973, PME-B); Ulmus stump by
ditch and farm, Hatches, Little Burstead (1974, PME-B); old field gate
and trunk of Fraxinus, Dunton Lodge, Herongate (1974, PME-B); Ulmus
stump by ditch at edge of disused barracks, Langdon Hills (1974, PME-B);
stumps of Salix and Ulmus and bole of Fraxinus, Westley Heights, Lang-
don Hills (1974, PME-B); horizontal surface of sandstone chest-tomb and
at mortar/sandstone niches, All Saints', Hutton (1974, PME-B); trunk of
old Ulmus in churchyard and on old Ulmus stump in hedgerow of adjacent
field, St Mary's, Runwell (1974, PME-B); on horizontal surfaces of garden
fence, 117, Norsey Road, Billericay (1974, PME-B).
Caloplaca aurantia (Pers.) Hellb.
Rare on limestone. 51/69, 79.
Vertical surfaces of limestone headstones in churchyards of All Saints',
Hutton (1972, PME-B) and St Mary's, Runwell (1974, PME-B).
C. citrina (Hoffm.) Th. Fr.
Very common on concrete, mortar, asbestos-cement and limestone;
occasional on marble, palings, decorticate stumps and bark of Ulmus and
Salix. 51/68, 69, 78, 79.
Throughout the whole area, especially in hypertrophicated sites e.g.
near arable land and bird-perching stones.