14 ARKIV FOR BOTANIK. BAND I]. w:o 3. 
Spore powder creamy. Spores hyaline, subglobose, asperu- 
late, l-guttate, 3—4x3 yw Hyphae soft, fibulate, 2—3 u. 
broad. — The whole plant very soft and fragile. 
BnEsADOLA's Poria subtilis seems to be identical, and 
SCHRADER’S plant with that name, which FRIES refers to Poro- 
thelium, might belong here, though this question can not be 
definitely settled without studying SCHRADER’S specimen. 
Whether this is still existing I do not know. At all events my 
plant is quite identical with a collection from CHAILLET in 
PErsoon’s herbarium, determined by PERSOON as »Bol. byssi- 
nus SCHRAD. Boletus molluscus Syn. Fung.» This last name 
»molluscus» could be accepted as very apt indeed, but in fact 
both PERsooN and FRIES have referred different things to Pol. 
molluscus, and BRESADOLA'S »Poria mollusca » is another species. 
I therefore use here the name given by BERKELEY and BROOME, 
though in my opinion not very apt, but founded on a specimen 
still existing in BERKELEY’S herbarium. 
In specimens collected in Femsjö (for instance Lrovp 
09203 and 09206) the hyphae are a little broader (2—4—6 u. 
or some cells even up to 10—20 u broad) and often sprinkled 
with crystals and small granules. The spores are also a little 
larger (3—5x3—3 '/, w), subglobose or ellipsoidal or even 
subreniform. 
P. igniarius. — Fig. 23 (spores). 
On dead and fallen trunks of Betula and Salix through the 
whole birch region. At Abisko some small specimens were 
found also on Populus (the hanging variety common on this 
host). 
Pores 4—5 or 3—5 per mm., on the inside armed with dark 
subulate spines of about 9—25x3—19 (generally 12—15x 
4—7) v. Spores hyaline, subglobose, 5—7 !/, x 4—7 v, often 
1-guttate. 
! [n a single specimen on Salix from Nuolja (marked 9.8.09: 20 E) I fail 
to find any hymenial spines. Else such spines seem to be a constant character 
in this species, though some authors doubt or deny their existence. I have 
examined a lot of specimens in this respect from Salix, Sorbus, Pyrus Malus, 
Populus, Alnus, Betula, Corylus, Acer ete. and in all (with the only exception 
just stated) I found the spines not only existing but even rather abundant. 
They are, however, generally not uniformly distributed over the whole inner 
surface of the pores, being often more copious at or near the bottom than near 
the mouth. For facilitating their detection it is advisable, therefore, to make 
sections in the longitudinal direction of the pores. — It is not the presence of 
