ACROSTICHOPTERIS. 61 
most features stands nearest to Acrostichum, much resembling the 
section Rhipidopteris. In this latter, however, the fructification 
is borne on separate pinnules. If we place the fructified pinnules 
of LRhipidopteris as basal segments on the sterile ones, we have 
a form strikingly like Acrostichopteris. The genus has also some 
resemblance to Warsilea.’’' 
It is doubtful if the generic name Acrostichopteris be the most 
suitable for such specimens as the English rocks have afforded. 
In Fontaine’s specimens there is some evidence as to fructification 
characters, but in the few fragments from Ecclesbourne there 
are no traces of fertile leaves. The similarity, however, between 
the American and English specimens appears to be exceedingly 
close, and the habit represented by the various species is not one 
which occurs very commonly among recent genera. 
In the recent species Acrostichum peltatum, Sw.,’? the sterile 
leaves have the same deeply divided pinnules with narrow segments 
as those of A. Fuffordi, but in the latter form there are several 
pairs of pinnules attached to one axis; the difference in the 
arrangement of the fertile pinnules has already been alluded to 
by Prof. Fontaine. 
It is difficult to determine whether such specimens as those 
described below should be spoken of as pinne of a frond with a 
creeping rachis, or as the pinnate leaves of a creeping rhizome, 
as in Acrostichum peltatum. I have placed the genus in the Poly- 
podiacee on the strength of Fontaine’s conclusions, drawn from 
much more complete material than the British Museum affords. 
The evidence as to family characters is best seen in the figures 
of American specimens; it is by no means all that could be desired. 
1.—Acrostichopteris Ruffordi, sp. nov. 
Type. Pinne and portions of rachis. In the British Museum. 
Main rachis probably creeping, bipinnate, pinne linear; pinnules 
alternate, rhomboidal or cuneate, deeply divided into narrow 
cuneate segments with acute or obtuse teeth. Venation of the 
Ctenopteridis type. No fructification preserved. 
1 Potomac Flora, p. 106. 
2 Fée, Genera Filicum, pl. ii. 
