62 CYATHEACE®. 
This species comes very near to <Acrostichopteris densifolia,} 
Font., but differs in the shape of the pinnules; in 4. Ruffordi 
they are less orbicular in form, but on the other hand shorter 
than in another Potomac species, 4. longipennis,* Font. 
Vigoct. El. VI. Fig.s, 
A single sterile pinna, or possibly a pinnate frond. The re- 
peatedly forked veins well shown, with their single branches in the 
narrowly linear ultimate segments. LEcclesbourne.  Lufford Coll. 
V. 2327a Fragments of pinne, also what is probably part of 
the main rachis of the frond showing the point of attachment of 
one pinna. Close to this portion of the rachis there is a flexuous 
structure which at first sight appears to be a continuation of the 
former piece; the two are, however, at slightly different levels in 
the ironstone matrix, but in all probability both may be regarded 
as fragments of the rachis; on the second piece there are here and 
there the beginnings of several lateral branches which may possibly 
be roots. Ecclesbourne. Rufford Coll. 
Family CYATHEACEZ. 
The oblique annulus and the transverse dehiscence of the 
sporangia are the chief distinguishing features of this family. 
The genus Matonidium, Schenk, may probably be regarded as a 
Wealden representative of the recent genus MMatonia, R. Br.; the 
latter, according to Baker,*® should be placed in a tribe by itself, 
and not united with the Cyatheacee. 
Genus MATONIDIUM, Schenk. 
[Paleontographica, vol. xix. 1871, p. 219.] 
This genus, founded on specimens of sterile and fertile fronds 
from the Wealden of North Germany, is thus defined :— 
‘Folia sterilia et fertilia conformia flabellato-pinnata, segmenta 
1 Potomac Flora, p. 107, pl. xciv. fig. 4; pl. clxx. fig. 11, ete. 
2 Ibid. p. 107, pl. elxx. fig. 10; pl. clxxi. figs. 1, 5 and 7. 
3 Annals Bot. vol. vy. 1890-91, p. 192. 
