BY R. ETHERIDGE, JUN. 
1307 
3. Didymosorus, Debey and Ettingshausen. 
Even more interesting than the plant just described is the third 
and last specimen from the Desert Sandstone of the Ci’oydoii 
goldfield, and which seems to be of a type rare in Australian 
Palfeontology. It is, I believe, identical with \X\^^'Pecopteris glti- 
chenoides, Oldham and Morris, Avhich should be placed in the 
genus Didymosorus, Debey and Ettingshausen,* * one of the Glei- 
cheniacese. This genus resembles the recent Gleichenia, but 
possesses a different fructification. The frond in Didymosorus is 
dichotomous and bipinnate, each division being very long, narrow, 
and nearly parallel-sided ; the pinnae are cpiite linear, either oppo- 
site, or sub-alternate, on a very narrow rachis. 
V' 
The typical species of Didymorsorus, D. com jotoni folia, D. and 
E., occurs in the Cretaceous rocks of Aix-la-Chapelle, whilst 
^ecopteris gleichenoides 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 w^e do not possess enough of 
the frond to show dichotomisation. It is either identical with the 
Indian species, or a mere variety of it, although it has points in 
common witli the European form. Unfortunately for the purposes 
of strict identification, 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 siz<i 
the specimens now' under description agree entirely with the Indian 
species, but seem to be rather smaller than the European, tlie 
general width of a pinna being two-sixteenths of an inch. 
The figures of Oldham and Morris* represent portions of fronds 
as long as seven inches, and two and a-half inches wide, but the 
largest of our specimens is four inches long, and one and a quarter 
• Denks. K. Akad. Wissensch. Wien, 1859, XVII. 1 Abth. j). 186. 
* Pal. Indica (Condwana Flora), I860, I. pt. 1, fas. 6. p. 45, t. 25, t. 26, 
f. 2 and 3. 
