55 
NEW BRITISH HYMENOMYCETES. 
By A. A. Pearson, F.L.S. 
The identification of all the species included in this paper 
has been confirmed by Monsieur |’Abbé H. Bourdot, to whom I 
am much indebted. His letters have been freely used in the 
notes dealing with Sebacina. The specific names are used with 
the significance given to them by Bourdot and Galzin in their 
papers in the Bull. Soc. Mycol. Fr. 
EXIDIA THURETIANA (Lév.) Fr. Hym. Eur. p. 694. 
Effused in thick undulating pulvinate or tuberculate patches 
of a firm gelatinous consistency; opalescent when fresh, some- 
times with a pink tinge; hymenium pruinose, finally collapsing 
into a thin horny yellowish film. Hyphae 1~23 p; basidia longi- 
tudinally septate 15-20 x II—I5 yu; spores hyaline, cylindrical, 
curved 15-20 x 5-7. Grows abundantly on the underside of 
beech sticks lying on the ground. 
The large spores and firm consistency are the distinguishing 
feature of this species. 
Horsley, Surrey, Feb. 1920; Painswick, Gloucestershire, May 
1920; Worcester, C. Rea, 1920. 
SEBACINA Tul. 
The species of Sebacina originally described possess a firm 
crust. The limits of this genus have, however, been extended 
to include mucous evanescent species. 
In Sebacina (sensu stricto) the coriaceous subiculum is some- 
times well developed, clavariiform as in Jaciniata Bull., cristata 
Pers., or like a Corticium as in imcrustans Pers., sebaceum Pers. 
It is now realised that these are all variations of the same 
species. 
But careful observation will show that the above forms, which 
are summer forms and often almost sterile, are replaced gradually 
in the autumn and winter by other forms where the coriaceous 
subiculum is reduced more and more until it disappears. The 
plant is then spread over the soil or débris and entirely gela- 
tinous-mucous. This form is probably the true Tvemella epigaea 
B. et Br. The same plant turned pruinose and bluish by 
abundant sporulation constitutes Sebacina caesia Tul. If 
growing on wood it might be the same as S. ambigua Bres. 
In all these plants the structure and the spores are the same; 
only the coriaceous hyphae so abundant on the first forms no 
longer exist in the last, where, however, the mucous hymenium 
