BY R. ETHERIDGE, JUN. 
1301 
narrow, long, rigid, and erect ; in the latter more or less flabellate, 
and to some extent spreading, or rather expanding. The pinnules 
in R. incequilatera are stiff, rigidly fan-shaped, and with strongly 
serrated edges, the veins after dichotomisation passing one to 
each division of the margin. But in our fern the leaflets are 
ovate-pyriform, with simple margins, and veins several times 
dichotomous. The result of this arrangement is that a much 
more graceful outline is given to a far laxer frond thau exists in 
Rhacopteris. 
The resemblance between the two ferns, so generally alike and 
yet so different in detail, gives rise to the question — to what genus 
should the Queensland plant be referred 1 A really scientific 
method has now come into vogue for the determination of fossil 
ferns by their fructification, when observable, a method far in 
a'lvaiice of the old separation, simply depending on the nervation 
and form of the pinnule, in conjunction with the form of the 
frond. In the present instance, the absence of fructification 
leaves no choice but to employ the form of the leaves and their 
arrangement as our guide. This undoubtedly brings our plant in 
close relation with the group of ferns represented by such genera 
as Cyclopteris, Archceopteris (= Pakeopteris), Rhaeopteris, Adian- 
tites (so-called), and others. The resemblance is specially strong 
to Cyclopteris and Adiantites, but I believe Prof. Gbppert, the 
author of the latter, abandoned his genus in favour of Cyclopteris. 
The most philosophical handling of this old Brongniartian 
genus, wliich has yet appeared, so far as the subject is known to 
me, is that by Principal Sir W. Dawson, F.R.S., who has given 
the following classification.* ^ 
Cyclopteris., Bronguiart (restricted), after the type of C. fiahdlata, 
Brong. Carboniferous. With three sections. ^ 
(a). ArclKHopteris, Dawson; typified by ^Cyclopteris hiher- 
itica, Forbes, and to supersede Schimper’s genus, Palmop- 
teris. The pinnules are ovate and decurrent on the 
rachis. Devonian. 
‘ The Fossil Plants of tlie Devonian and Upper .Silurian Formations of 
Canada, Geol. Survey Canada, 1871, p. 48. 
