62 THE ESSEX NATURALIST.
OCCURRENCE OF COLLODERMA OCULATUM
(LIPPERT) G. LISTER IN EPPING FOREST.
By Joseph Ross.
In the autumn of 1912 Miss G. Lister pointed out to me
some sporangia of Colloderma oculatum on the moss-grown bole
of a tree in Epping Forest, near Debden Green. Soon after-
wards I found the species on fallen logs in the Forest near
Chingford, and since then it has occurred repeatedly in this
neighbourhood. In a comparatively small area it has been
found on four logs and three living trees. It has also to my
knowledge appeared on one other log and on three other living
trees between Chingford and Fairmead Bottom. From one log
on which it occurred in 1912 and 1913 it disappeared after a
few years, at least I failed to find it; moss and liverwort have
been growing on this log for twenty years, Trichia botrytis and
Physarum vivida also occurred on it. In the autumn of 1932
Colloderma oculatum again appeared on knotted wood at the
crown of the log, about a yard away from where it was first
seen; Trichia botrytis occurred close to it.
Within two yards of this log lies another, without any growth
of moss or liverwort; except for a few scattered sporangia of
Comatricha nigra no mycetozoa occurred here until four or five
years ago. Then C. oculatum and T. botrytis appeared and
continued to do so until 1931, when Licea flexuosa13 also occurred
there. Last summer (1932) this log was rolled over; when, in
November, it was turned back to its earlier position C. oculatum
was again found on a moist part.
In 1917 oak bark lying beside another log not far from the
Cuckoo Brook produced fine developments of Diderma floriforme.
Some years later C. oculatum appeared on this log also and has
continued to do so amongst liverwort and lichen to the present
time.
Naturally this species disappears from living trees when for
any reason the trickle of water down the trunk, which enables
it to develop, ceases to flow.
Colloderma oculatum was first recorded in Britain in 1910,
and in Epping Forest in the following year. It is interesting to
find that it may haunt the same log for so long a period as twenty
years.
13 This was the first Essex record of this species.—ED.