226 LISTER I THE STUDY OF MYCETOZOA IN BRITAIN. 
yellow species has been recorded from Essex. It was found 
by Mr. J. Ross on holly leaves, August 1915, in the forest near 
Chingford. 
Leocarpus fragilis (Dicks.) Rost.—Abundant in autumn 
on sticks, bracken, heather, etc. The yellow plasmodium often 
creeps far from its feeding grounds to find a suitable place in 
which to fructify and scatter the spores. 
Diderma effusum (Schwein) Morg.—Not uncommon on 
dead leaves, especially those of holly, from June to September. 
D. radiatum (L.) Lister var. umbilicatum Meylan.— 
The type of this species in the Linnean Herbarium has brown 
sporangia dehiscing by stellate lobes, a form far less frequent 
in Britain than one with grey sporangia which open irregularly l 
the latter form was described by Persoon as Diderma umbilicatum ; 
although growths showing intermediate characters are not 
rare, it is well to recognise the form with grey sporangia as 
representing a distinct variety ; I follow M. Ch. Meylan in 
adopting the varietal name umbilicatum . X1 This variety 
is not unfrequent in autumn and mild winters on dead bramble 
leaves, stems and twigs ; the greyish or white sporangia are 
usually grouped in small scattered clusters. 
D. floriforme Pers.—Probably not uncommon on old stumps 
from June to December. 
Diachaea leucopoda (Bull.) Rost.—Not uncommon from 
August to November on heaps of dead leaves and twigs ; some¬ 
times the cylindrical white-stalked sporangia occur in great 
profusion, developing from large plasmodia. 
Didymium difjorme (Pers.) Duby.—Common on heaps of 
decaying leaves and dead herbaceous plants, almost 
throughout the year. 
D. Clavus (Alb. & Schw.) Rabenh.—Abundant on dead 
leaves in summer and autumn ; also occurring on the trunks 
of living trees among moss. 
D. complanatum Rost.—Apparently rare, but possibly 
overlooked from being mistaken for a plasmodiocarp form 
of D. squamulosum, which it outwardly resembles. Found in 
Wanstead Park in summer on dead leaves, developing from 
lemon-yellow plasmodium. 
11 See Meylan, 11 Myxomycetes du Jura,” in L’Aimuaire du Conservatoire et du Jarditr 
botanique de Geneve, 1913, p, 312. 
