CHAPTEE XXXIV. 
THE OEGAHIC REMAINS OP THE DESERT SANDSTONE FORMATION 
(UPPEK CRETACEOUS), 
"With Desceiptious op the Species. 
Kingdom — PLANT.®. 
Section-CRYPTOGAMI®. 
Class — Acottledones. 
Order-FILICES. 
Family— OLEICHENIACE^. 
Qenus — DIBYMOSOBTJS, Belay and Btting&liausen, 1859. 
(Denk. K. K. Akad. Wissensch. Wien, xTii., 1 Abth., p. 186.) 
Didtmosoees ? GLEicHENiorDES, Oldham and Morris, var. 
Pccopteris [Gleichenites] linearis, O. and M., Mem. Geol. Survey India, ii., p. 324. 
, „ gleichcnioidcs, 0. and M., Pal. Indica (Gondwana Flora), 1862, i., Pt. 1, p. 45, t. 25, 
t. 26, £. 1, 3. 
Gleichenites {Gleiehenia) bindrabunensis, Feistraantel, Ibid., j). 93. 
Gleichenia bindrabunensis, Schiniper, Traite Pal. Veg., 1869, ii., p. 6/0. 
dyidymosorus ? glcichenioides, Etheridge fil., Proc. Linn. Soc. !N. S. Wales, 1888, iii., Pt. 3, p. 1308, 
t. 38, f. 3. 
Sy. Char. Frond [bipinnato] long, narrow, parallel- sided, tapering but very 
slowly. Pinuffi long and linear, opposite or sub-alternate, rarely alternate, obtusely 
pointed at their apices, springing from the rachis at right angles, and in close contiguity 
to one another. Rachis straight, non-flexuous, small and delicate. Pinnules short, 
entire, broad-ovate, sub-alternate on the piniue, and decurrent. 
Obs. The present plant is, I believe, identical with the Becopteris gleichenioides, 
Oldham and Morris, which should be placed in the genus Bidymosorns, Debey and 
Ettingshausen,* one of the Gleicheniacea). This genus resembles the recent Gleiehenia 
but possesses a different fructification. The frond in Bidymosorns is dichotomous and 
bipinnate, each division being very long, narrow, and nearly parallel-sided ; the piuns 
Me quite linear, either opposite, or sub-alternate, on a very narrow rachis. 
The typical species of Bidymosorus, B. compfonifoUa, D. and E., occurs in the 
Cretaceous rocks of Aix-la-Chapellc, whilst Beeopteris gleichenioides is found in the 
Mesozoic rocks of the Rajmahal Series of India. 
The Australian plant corresponds with the description of the genus in every 
particular, but we do not possess enough of the frond to show dichotomisatiou. It is 
either identical with the Indian species, or a more variety of it, although it has points in 
common with the European form. Dnf'ortunately for the purposes of strict identifica- 
tion, the specimens are preserved in a fine siliceous grit, which has obliterated all evidence 
of fructification, if any such existed, and also of the nervation. As regards size the 
* Denks. K. Akad. Wissensch. Wien, 1859, xvu., 1 Abth., p. 186. 
