106 Proceedings of the Royal Physical Socvety. 
Haughton, on the one hand, and from Psilophyton on the 
other—where in the latter genus the fructification consists 
of “naked oval spore-cases, borne usually in pairs on slender 
curved pedicels.” The affinities of <Arthrostayma appear, 
however, to be closer to Psilophyton than any other known 
genus. If the fruit of Arthrostigma consisted of a spike of 
spore-cases arranged in two rows, which I am inclined to 
think is the correct explanation of its structure, we may 
then compare it to the fructification of Psilophyton—where 
the naked sporangia were borne generally in pairs at 
the ends of the branches, whereas in <Arthrostigma the 
sporangia (apparently without accompanying bracts) were 
arranged in two rows, one row on each side of a common 
axis. 
No remains of fructification were found with the Perth- 
shire specimens, but in connection with this subject attention 
may be drawn to the figure of a “ Fern (?) of Lower Old Red 
Sandstone, Orkney,” given in the “ Testimony of the Rocks” 
(in 1857 edition), p. 25, fig. 13, and described at p. 431 as 
follows :— 
“Tn the flagstones of Orkney there occurs, though very 
rarely, a minute vegetable organism, which I have elsewhere 
described as having much the appearance of one of our smaller 
ferns, such as the maidenhair-spleenwort, or dwarf moonwort. 
It consists of a minute stem, partially covered by what seems 
to be a small sheath or hollow bract,! and bifurcates into two 
fronds or pinne, fringed by from ten to twelve leaflets, that 
nearly impinge on each other, and somewhat resemble in their 
mode of arrangement the leaflets of one of our commonest 
Aspleniums—Asplenium trichomanes. One of our highest 
authorities, however, in such matters, (the late) Professor 
Balfour of Edinburgh, questions whether this organism be in 
reality a fern, and describes it, from the-specimen on the 
table, in the Paleeontological chapter of his admirable class- 
book, simply as ‘a remarkable pinnate frond.’” 
The specimen referred to above was figured in an earlier 
work by Hugh Miller, the “ Footprints of the Creator” (3rd 
edition), 1850, p. 193, fig. 56. The description is not so fully 
1 This supposed bract appears to be only a separated portion of the stem. 
