102 THE ESSEX NATURALIST.
Craterium minutum (Leers) Fries. Frequent.
C. leucocephalum (Pers.) Ditm. This somewhat infrequent
species for Epping Forest was found in the second part of the
area, where apparently there was more than one development.
Many sporangia seemed to have been formed in unfavourable
conditions : some were brown from absence of lime ; some had
a depression at or near the centre of the top, and some very large
ones were furrowed across the top, or showed three furrows
meeting in the centre of the top. The furrowed sporangia
were supported by two or three stalks, and were probably due
to several sporangia having coalesced and developed irregularly.
The typical form of C. leucocephalum is the one Miss G. Lister
has described as "egg-in-eggcup," from which the lid, that
is the part of the egg extending beyond the cup, becomes
detached when the organism weathers. In the gathering of
which I am writing there were numerous subglobose sporangia
dehiscing irregularly almost to the base. The very varied forms
of the sporangia made them an interesting study, but their
diversity suggests that it would be wiser to consider the many
abnormal ones as "sports" rather than that some of them
should be regarded as the established and described var.
scyphoides. The occurrence of specimens with two or three
stalks supporting a single sporangium recalls similar "sports"
of Didymium squamulosum found in the copse some years ago.5
Diderma spumarioides Fries. One colony on a beech leaf.
D. deplanatum Fries. One specimen found.
D. radiatum (L.) Morgan var. umbilicatum Meyl. Several
gatherings, one on a green ivy leaf.
Didymium difforme (Pers.) Duby. Miss Lister showed this
species to me many years ago on poplar leaves at Bush Wood,
and I have found it on poplar leaves at the Warren, but in the
past season it occurred on a variety of leaves amongst brambles,
and usually on leaves other than poplar.
D. Clavus (Alb. & Schw.) Rabenh. Two gatherings, each of
a few sporangia.
D. nigripes (Link.) Fries. A few weathered specimens.
5 In warm climates many developments consist entirely of well-formed var. scyphoides.