56 



BRITISH EOCENE FLORA. 



determination. It is apparently an oval leaf, sessile on a stem, something like Vota- 

 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. 



II. A fragment of a leaf (tig. 27), from Reading was figured, together with 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 

 Asplenium 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 Gleiche?iia, 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 differences. 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 



