EOCENE FERNS. 



29 



(b) Polypodiea. 



Gen. — PoDOLOMA, Elt. 



Filices herbacea, fronde simplici, Integra ; sporant^ia nervis imposita, in soros sub- 

 rotundos sparsos indusio nullo obtectos collecta. Nervatio Phlebodii irregularis. 



PoDOLOMA POLYPODioiDES, Eit. and Gard. Plate III, figs. 4, 5, G, and 9. 



P. fronde submembranacea, lanceolata vol linear i-lanceolata, integerrima^ utrinque 

 angustata ; nervatione Phlebodii irregularis ; nervo primario rhaclddromo, recto, promi- 

 nente, apicem versus sensim attenuato, nervis secundariis sub angulis 55 — 65° orientibus 

 brochidodromis ; maculis medianis vix distinctis, incBqualibus ; laqueis PJdebodii semi- 

 ellipticis, incequalibus ; maculis later alibus irregularibus viinutis, 1 — 3 seriatis ; appen- 

 dices nmuerosos tenuissimos ramosos includentibus. 



Middle Bagshot, Bournemouth. 



This genus and the next approach the Dictyopteridece of the older floras and certain 

 recent tropical species of Polypodium belonging to the sub-genus Pliyma- 

 todes, namely, P. lycopodioides, P. persicaricefolium, P. salicifolinm, P. 

 transparenSy and P. hemionitideum. The leaves may be distinguished from 

 dicotyledons, notwithstanding their superficial resemblance, as, independently 

 of the remains of spore-cases, they possess the peculiar venation of this 

 section of Polypodium. 



The frond represented in PL III, fig. 9, offers points of agreement in 

 form, texture, and venation, with the barren frond of the recent Polypodium 

 lycopodioides. The fossil presents the Phlebodium type of venation, modified 

 by a less uniform shape and by the inequality of the meshes abutting on 

 the midrib, which hardly differ from the rest. The Phlebodium loops are 

 irregularly arranged and of unequal length and breadth. The two to three 

 rows of marginal meshes, instead of being elliptical, are irregularly angular, 

 and filled with numerous free and anastomosing venules (PL III, fig. 5). 

 These differences are the bases of a new type, deviating essentially from the 

 Phlebodium appendiculatum to which P. lycopodioides belongs, and is called 

 Phlebodium irregulare. Figs. 4 and 9 are of natural size, and show the "^'po(iiddes.^'^°" 

 general form and average size of the pmnae. Fig. 5, which is the base of a pinna enlarged, 

 accurately shows the venation in detail, and, in three places, what appear to be sori in 

 an early stage of development, around which the arrangement of meshes is peculiar. 



