76 Ona Specimen of Pecopteris (? polymorpha, Brongn.). 
In a paper on Sphenopteris afiinis, L. & H.*, Mr. C. W. 
Peach gives some good figures of the young state of this 
fern. His figures 6 and 7 show very clearly the character- 
istic dichotomy of the rachis of this species. 
The above is a list of the chief Paleozoic examples of Sp7- 
ropteris which have been figured and described ; and it is re- 
markable, that though ferns are our most common class of 
fossil plants in the Carboniferous formation, specimens show- 
ing their early stages of development are so seldom met with. 
There is another group of fossils which, though very similar 
in general appearance to Spiropterts, are most probably quite 
different in nature. For these Schimper has proposed the 
name Rhizomopteris T. 
In this genus Schimper places the specimens which Geinitz 
has figured} as Selaginites Erdmanni, believing them to be 
fern-rhizomes; and certainly the fossils in question have a 
great resemblance to such structures. 
There can be no doubt as to Geinitz’s plants being quite 
distinct from those originally described under the same name 
by Germar §. 
Schimper also places in his Rhizomopteris the Selaginites 
uncinnatus, Lesqx. ||. 
Lesquereux, though he says the specimen cannot posi- 
tively be referred to the Lycopodiacez, still keeps it separate 
from Rhizomopteris, and includes it in Lycopodites (L. un- 
cinnatus) 4. 
I am inclined to regard this fossil as the rhizome of a fern ; 
and the spiral terminations of several of the branches, which 
appear to be the chief character that prevents Lesquereux from 
regarding his plant as a rhizome, are most probably spirally- 
coiled young fronds springing from the points of the branchlets 
of the rhizome. 
From the nature of the fossil and the state of its preserva- 
tion, there is, however, room for difference of opinion as to its 
true nature. 
* Quart. Journ. Geol. Soc. vol. xxxiv. p. 131, pl. viii. figs, 5-7. 
+ Schimper, /. c. vol. i. p. 699 (1869). 
t Geinitz, /.c. pl.i. figs. 5 and 6. 
§ Geinitz figures in his ‘ Flora der Kohlenform. v. Hainichen-Ebersdorf 
u. Fliher-Guckelsberg,’ p. 56, pl. xiv. fig. 20, a plant which he also names’ 
S. Erdmanni. This appears to be only a badly-preserved Lepidodendron. 
|| Geol. Survey of Illin. vol. ii. p. 446, pl. xli. fig. 3 (1866). 
q ‘ Coal-Flora of Pennsylvania,’ p. 359 (1880). 
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