56 
BRITISH EOCENE FLORA. 
determination. It is apparently an oval leaf, sessile on a stem, something like Pota- 
mogeton. The venation is " Cyclopteris" and therefore cannot be that of a Monocotyledon, 
and, although obscure, is seen to be converging, and the veins may have been united to 
the stalk. In one place, near the base, a distinct forking is seen. Heer regards it as 
referable to Alisma or Potamogeton. 
11. A fragment of a leaf (fig. 27), from Reading was figured, together vrith others, 
by Professor Prestwich, in the ' Quart. Journ. Geol. Soc.,' vol. x, 
pi. iv, fig. 11. Sir Joseph Hooker, who examined it, remarks (op. 
cit., «p. 166) that it resembled a fragment of a Fern frond, "but 
equally well represents a portion of the pinnatifid leaf of a 
composite or umbelliferous plant, and may, indeed, be referred 
to very many other natural orders." Leaves of composite or umbel- 
liferous plants, however, are not met with in the Eocenes, while Ferns 
are seldom absent from any assemblage of their vegetable remains ; 
since, therefore, the form closely approaches to that of some Ferns, as 
Aspleniiim dimorphum, &c., it seems most probable that its place is 
among them. It bears a resemblance to forms, from the supposed 
Cretaceous rocks of Greenland, described by Heer as Jeanpaulia. 
III. PI, X, fig. 7, represents the only fragment of Fern yet found at Bromley. It 
might be placed in Aspidium or Gleichenia, and there are fossil forms figured in Heer's 
' Arctic Floras ' with which it could possibly be united. 
IV. There are, in addition to the Ferns described above, indications of a variety of 
other forms from Bournemouth, which we have thought too uncertain or fragmentary 
to be worth including in our descriptions. Three of these appear to be Polypodia, 
one recalling P. serpens and another P. bifrons. 
Fig. 27. — Fern leaf 
from Reading, after 
Prof. Prestwich's 
figure. 
Perhaps the most striking fact brought to light during the progress of our work thus 
far, is the identity, or at least similarity, of the majority of our British Eocene Ferns with 
those of other fossil floras containing dicotyledons, already described from Europe or 
America. All of them are well represented elsewhere, with the exception principally 
of our group of Phymatodes, Hewardia, and Marattia. This, and other facts con- 
nected with them, will be best brought out by tabulating them according to Sir W. 
Hooker's classification (omitting, however, all those about whose determination we feel 
any degree of doubt), and uniting with them their fossil allies. Although each of the 
groups so composed only comprises forms which might apparently be united, since they 
seem to come within the limits of variation seen in analogous species of existing Ferns, 
yet it is most desirable to retain all specific names which mark constant difierences. Not 
only may these become of the greatest value in determining the relative ages of fossil 
floras in the absence of stratigraphical evidence, but by a due appreciation of the slight, 
but progressive changes in what must, in a broad sense, be considered as the same species 
