870 DR R. KIDSTON AND PROF. W. H. LANG ON OLD RED SANDSTONE PLANTS 
gradually from their hyphal stalks. Diameter of hyphal stalk, up to 24 n. Trans- 
verse diameter of vesicle, up to 100 n. 
Occurred in a decayed portion of a stem of Rhynia Gwynne-Vaughani. 
Locality. — Muir of Rhyme, Aberdeenshire. 
Horizon. — Old Red Sandstone. (Not younger than the Middle Division of the 
Old Red Sandstone of Scotland.) 
Palseomyces agglomerata, Kidston and Lang, n.sp. (PI. IY, figs. 39-41. 
Slide No. 2533.) 
Fine hyphse attaining a diameter of 5 m, with terminal or intercalary dilatations 
giving rise to spherical thin-walled resting-spores 40-50 m in diameter, that often 
occur in irregular masses. 
Occurs in the tissues of all the vascular plants of the Rhynie deposit, but 
especially in stems of Rliynia Gwynne-Vaughani and in the matrix in connection 
with them. 
Locality. — Muir of Rhynie, Aberdeenshire. 
Horizon. — Old Red Sandstone. (Not younger than the Middle Division of the 
Old Red Sandstone of Scotland.) 
From the systematic point of view the fungi which have been described above, 
and to some of which specific names have been given, add little to our knowledge. 
While providing beautifully preserved and abundant examples of mycelium and 
resting-spores in the decaying parts of plants in the silicified peat, their type of 
construction is, on the whole, similar to those fungi already known from Carboni- 
ferous rocks. Their Early Old Red Sandstone age, however, gives them an 
increased interest. 
The general characters of these fungi suggest a systematic position with the 
Phycomycetes, and probably (though there is no definite evidence for this) with 
the Oomycetes. The mycelium seems to have been typically non-septate. The 
one example in which transverse septa were fairly frequent and well marked 
appears exceptional among the numerous specimens examined, and this mycelium 
resembles in other respects the non-septate mycelium found in a corresponding 
position. The formation of septa, in addition to those formed in the development 
of reproductive organs, is well known to occur among existing Phycomycetes, and 
we do not feel justified in laying stress on this character by itself. While 
characteristic asexual or sexual reproductive organs are wanting, the type of 
resting-spores (chlamydospores), which, when immature, often appear as terminal 
vesicles, can be. best paralleled among existing Phycomycetous fungi. 
The only systematic conclusion that we appear to be warranted in drawing 
from the rich assemblage of fungal mycelia, vesicles, and resting-spores in the 
Rhynie peat is that the occurrence of Phycomycetes already established for the 
