BY R. M. JOHNSTON, F.LS. 175. 
(Thinnfeldia obtusifolia, mihi) from the mesozoic shales, 
and not the form from the coarse sandstones examples of 
which are very rare. 
As an illustration of the rarity of the latter, I may state 
that my own experience among Tasmanian rock extends over 
twenty-two years, and in that time I have only obtained 
about a dozen specimens of Prof. Morris’ original types, 
always in the sandstone matrix; never in the shales. All of 
the casts of specimens agree ‘with Prof. Morris’ originals, 
which are invariably coarse, never show dichotomy, and 
frequently the pinnules, unlike the common 7. obtusifolia, 
indicate a trace of a pretty well defined mid-rib. 
With such doubt respecting these two forms, which are 
merged together as one species by Dr. Feistmantel in his last 
memoir on “ The coal and plant-bearing beds of Paleozoic 
and Mesozoic age in Hastern Australia and Tasmania, pp. 
101-105.” I think it advisable to retain the original name 
of Pecopteris odontopteroides (Morris) for the rarer original 
type until such time as we obtain better evidence as to its 
identity. 
To aid in this direction I have figured such of the fragments 
of the older and rarer fern as are still in my collection (pl. ii, 
figs. 1-5), all of which have been obtained from the sand- 
stones of the Jerusalem basin. Like Professor Morris’ speci- 
mens, the blackened impressions alone exist. There are 
traces of what appear to be a well-defined mid-rib in several 
of the pinnules, but in no example have I seen any indication 
of dichotomy of the terminals of the pinne, so constant a 
character in the smaller abundant form—Thinnfeldia obtusi- 
— folia (mihi). 
Dr. Feistmantel has also, in the memoir already referred to, 
included another form under Thinnfeldia odontopteroides 
(Mourns) vay., figs. 1, 1° 12.2) .2* 2° Pl. xxix; fies. 1, 1%, 1, 
2, 2°, Pl. xxx., whose identity with either P. odontopteroides 
(Morris), or T. obtusifolia (mihi), is morethan doubtful. The 
robust branching fern from Victoria, and New South Wales, the 
Hawkesbury series certainly approaches T. obtusifolia (mihi) 
in the upper pinne, but while 1 recognise the rare judgment 
and wide knowledge of Dr. Feistmantel, I am still doubtful 
whether the two forms are conspecific. The complete absence 
of dichotomy, in the terminal pinne, and the more robust 
character of this fine fern contrasts widely with T. obtusifolia 
(mihi), which, from the detached remains, never found in a 
branching connection, indicate probably repeated dichotomy, 
as in our existing Gleichenia flabellata, as suggested by 
Professor Morris. 
For this reason I think it would be well at present to dis- 
tinguish the splendid robust form from Mount Victoria by a 
separate name, say Thinnfeldia Feistmantelli, in honour of 
