— i8 — 
Effect of the Katmai eruption * 1 on Mosses. — Since the great eruption 
in 1912 of the volcano Katmai, Alaska, R. F. Griggs has directed expeditions 
to that region, and among several articles relating to these expeditions one is 
of more strictly botanical interest, 1 and it is interesting to note what progress 
the mosses may ha\e made towards recovering their former important place 
in the vegetation of the region. 
The thick mantle of volcanic ash transformed much of the region into a 
bleak desert, but in the last few years considerable vegetation has appeared, 
coming not from seedlings but mostly from plants of the previous vegetation 
which have been able to survive more or less complete burial. Sphagnum bogs 
have been almost completely destroyed, even when covered by but two or three 
inches of ash, and here, as elsewhere, the common horsetail ( Equisetum arvense) 
has assumed considerable importance as a ground-cover. In speaking of the 
forest, Griggs says: 
“In the deeper parts of the forest the branches bore great masses of moss, 
which, of course, caught and held quantities of ash. During the interval that 
has followed the moss has grown out over the ash, making larger masses than 
ever and giving the trees a very bizarre appearance. 
“The most striking feature of the revegetation of the forest, however, is 
to be found on the ground. When the ash dried out after the first heavy rains 
following the eruption, deep cracks appeared like the mud cracks in a dried-up 
puddle. These cracks are, of course, long since filled up by drifting ash, but a 
heavy growth of moss (Amblystegium sp.) has come up in every crack, giving 
the ground a most curious reticulated appearance. 
“This curious distribution of moss is apparently due to the fact that the 
spores found lodgment in the cracks. The same moss often starts around fallen 
sticks or other objects on which wind-borne spores would settle. One of the 
most striking instances of this was a sea-urchin shell, dropped by a raven and 
which was embedded in a mass of moss that had grown up around it.” 
O. E. J. 
Riddle on Pyrenothrix nigra 1 — I find no reference in our file of The Bry- 
ologist to the new genus and species, Pyrenothrix nigra, described by Dr. Lincoln 
W. Riddle in 1917, from material collected in Florida in 1897 on bark of scrub 
oaks and on living oleander by Prof. Roland Thaxter. Riddle says:“ On account 
of the distinctive combination of a byssine thallus and a pyrenomycetous fruit 
this new genus may appropriately be named as follows: Pyrenothrix, ge n. nov. ” 
The new lichen has gonidia of the Scytonema type and fruit of the perithecial form, 
evidently belonging to the family Pyrenidiaceae, but differs from all other genera 
in that family by the byssine character of the thallus and the muriform spores. 
“The structure of the thallus and the relation of hyphae and gonidia are seen to 
be exactly that of Coenogonium . ” The thallus is “brownish-black, spreading 
over the substratum without definite limits and closely adnate, byssine, when wet 
soft and gelatinous, when dry harsh and not at all spongy. ” 
1 Griggs, Robert F. Scientific Results of the Katmai Expeditions of the National Geographic 
Society. I. The Recovery of Vegetation at Kodiac. Ohio Journ. Sci. 19 : 1-57. Nov., 1918. 
1 Riddle, Lincoln W. Pyrenothrix nigra, Gen et Sp. Nov. figs.4 Bot.Gaz. 64: 513 -SiS- 19x7 
