30 BRITISH EOCENE FLORA. 



Eig. 6 is another fragment, further enlarged, showing small spherical markings, which 

 require further elucidation. 



PoDOLOMA AFFiNE, Mt. and Gard. Plate III, figs. 7, 8. 



P. fronde memhranacea, lanceolata integernma ; nervatione Phlebodii irregularis; 

 nervo primario rhacMdromo, recto, prominente, apicem versus sensim attenuato ; nervis 

 secundariis sub angulis 30 — 45° orientibus Jlexuosis brochidodromis, maculis medianis non 

 distinctis, laqueis PJdebodii irregularibus, inaqucdibus ; maculis lateralibus incequalibus, 

 1 — 2 seriatis, appendices nmnerosos tenuissimos ramosos wcludentibus. 



Middle Bagshot, Bournemouth. 



This is of a more delicate and membranous texture than the preceding, a distinguishing 

 character in itself. In addition the secondary veins diverge at a more acute angle, are 

 slightly sinuous, of unequal length, and at different distances apart. The median meshes 

 which characterise the Phlebodium venation, discernible in the preceding species, are not 

 perceptible in this, but in the magnified figure (PI. Ill, fig. 8) a number of very 

 irregular meshes are seen abutting on the midrib and taking the place of these median 

 meshes. The Phlebodium loops, as well as all the meshes, are very irregular and unequal 

 in form and size. The dots, visible without a lens, are evidently the bases of attachment 

 of sori. 



These two forms of Polypodiese are found massed together in layers in the highest 

 freshwater beds, immediately underlying the marine beds. Dicotyledonous leaves seldom 

 accompany them, but they are generally associated with torn fragments of aroids, rushes, 

 and conifers, and occasionally with remains of other ferns, as Osmunda, Fteris, and 

 Chrysodium. The venation is usually well preserved and distinct, but the pinnules are 

 always detached and the fructification removed, as if by maceration. The separating 

 layers are so thin and brittle, and the leaves so crowded together, that it is extremely 

 difficult to secure good specimens. The recent Polypodia with which they have been 

 compared have long creeping rhizomes, with simple and persistent fronds, not articu- 

 lated ; but the fact that in the fossils the pinnules are invariably detached and in layers 

 suggests that they belonged to annual ferns with articulated pinnae. Their geological 

 position and the leaves associated with them suggest that they inhabited swampy districts 

 near the sea-shore. 



Saporta, in a letter full of valuable comments, points out the resemblance which 

 Podoloma bears to the dicotyledonous BIyrsinice, Sapotacea, and the genus Bumelia. 

 The venation, however, seems to differ more from any of these than from that of some 

 existing Eerns. The existence of sori, besides, seems placed beyond doubt, lleer also 



