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-cost;eform, 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 revolute. 



Several microscopic sections of portions of fronds were made 

 with more or less satisfactory results. In PL 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 1'45 

 mm., the thickness in the centre 0'17 mm., and the thickness of 

 the ends, including the revolute portions, is 03 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 setiform hairs. I 

 cannot distinguish either stomata or the parenchymatous meso- 

 phyll 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 

 I'egular 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 toHuosa and P. torquis (Rec. Austr. Mus., 

 iii.. No. 5, 1S99, pp. 121 and 126), but if of this nature, distinct from either 

 of these forms. 



