A FERN FORMING A NEW GENUS — ETHERIDGE. 
139 
to the caudex, and is at once distinguishable from the frond proper 
by the absence of fascicles, and narrower proportions transversely. 
The largest number of fronds in any one whorl is twelve, ordinarily 
there are eight. 
The venation is very characteristic and stable throughout the 
whole of the specimens. A strong midrib, or costa, was present 
continuous to the apex, but perceptibly decreasing in thickness 
upwards. The fascicles are free and bilaterally symmetrical, the 
largest number observed on any one frond being twelve, but the 
usual number is eight. The veins are short, sub-internal, equal 
on each side, non-cos teeform, and rising at a very acute angle. 
The first bifurcation gives rise to two veinules, which are long and 
excurrent, following an upward and outward direction, the anterior 
always the longer of the two. The latter is almost invariably dicho- 
tomous, the posterior sometimes so, more often single, the resulting 
veinlets being short. There is, however, one very characteristic 
feature — the posterior veinule of the first fascicle on each side is 
always unbranched, and further, the veins of the first facicles are 
always the longest in each frond, springing from the costa well 
within the stripe, and remaining subparallel to the former. The 
margins of the fronds are at times re volute. 
Several microscopic sections of portions of fronds were made 
with more or less satisfactory results. In PI. xxvii., fig. 16, which 
is a section transverse to the line of growth, the general form of 
the frond is admirably shown, the revolute lateral margins, and 
the median longitudinal depression occupied by the mid-rib; none 
of the leaf tissues are preserved. The width of this frond is 145 
mm., the thickness in the centre 0T7 mm., and the thickness of 
the ends, including the revolute portions, is 0 3 mm. PI. xxvii., 
fig. 15, is a longitudinal section of a frond, or one parallel to its 
line of growth, and of special interest from the fact that the 
cellular tissue of the epidermis is to some extent visible, and both 
the upper and lower surfaces are clothed with setiforrn hairs. I 
cannot distinguish either stomata or the parenchymatous meso- 
pliyll of the frond. There are certain peculiar and equidistant 
tissue-pillars, extending transversely for half-way between the 
upper and lower surfaces, which appear to be composed of much 
decayed tissue, and enclose clear vacuities that certainly possess 
determinate margins ; one at the end of the section is filled with 
amber-brown pulverulent matter. The space below these pillars, 
extending nearly the whole length of the frond, does not show any 
regular parenchyma, but has distributed throughout it a number 
of straight or curved filaments.* A second longitudinal section 
* These filaments are not unlike the fungal borings described by me 
under the names of Palceachlya tortuosa and P. lorquis (Rec. Austr. Mus., 
iii.. No. 5, 1899, pp. 121 and 126), but if of this nature, distinct from either 
of these forms. 
