868 DR R. KIDSTON AND PROF. W. H. LANG ON OLD RED SANDSTONE PLANTS 
Gordoni and P. Gordoni var. major , have much in common with the type of 
Palseomyces agglomerata, and may be placed beside it without prejudice to their 
probably including a number of distinct kinds. 
Brief diagnoses of these named forms may now be given before entering upon 
some general considerations on the Rhynie fungi. 
The generic name Palaeomyces # is employed here as a “ useful and comprehensive 
designation ” under which to place fossil fungi, of the precise systematic position 
of which there is insufficient evidence. It is, therefore, not further defined, but 
the fungi from the Rhynie deposit that are described below as species of this genus 
agree in their usually non-septate mycelium bearing spherical or oval vesicles or 
resting-spores. 
In the case of each species a particular slide in the Kidston collection is cited 
that can be regarded as the type specimen. Most of the species occur more or less 
frequently in preparations of the Rhynie chert. 
Palseomyces Gordoni , Kidston and Lang, n.sp. (PI. I, figs. 6-11. Slide No. 2522.) 
Hyphse usually non-septate (in some cases probably septate) ; branched ; branch- 
ing without relation to the septa, if present ; ranging in diameter from about 6 n 
to 24 m. 
Resting-spores developed from vesicular swellings on hyphse ; usually terminal ; 
wall thick, differentiated into layers, and usually by contraction of the inner layer 
giving a double contour to the spore as seen in section. Mature resting-spores show 
considerable variation in size, but average about 240 n by 210 m. Occurs in the 
more or less decayed tissues of Asteroxylon, Rhynia, and Jlornea. 
Locality. — Muir of Rhynie, Aberdeenshire. 
Horizon. — Old Red Sandstone. (Not younger than the Middle Division of the 
Old Red Sandstone of Scotland.) 
Palaeomyces Gordoni var. major, Kidston and Lang. (PI. II, figs. 12 and 13. 
Slides Nos. 2527, 2479.) 
Spherical resting-spores ; variable in size ; up to 550 n in diameter ; wall about 
50 m in thickness, stratified ; borne on stalk-like portion of hypha about 50-60 n 
in diameter. 
Occurs in the more or less decayed tissues of Rhynia Gwynne-Vaughani and 
other plants, and sometimes isolated in the peaty matrix. 
' Locality. — Muir of Rhynie, Aberdeenshire. 
Horizon. — Old Red Sandstone. (Not younger than the Middle Division of the 
Old Red Sandstone of Scotland.) 
* Seward, loc. cit. 
