EOCENE EERNS. 



27 



Numerous short, contiguous, intricately anastomosing, fine veins 

 proceed from a prominent midrib, at angles more acute on the 

 less developed pinnse towards the apex of the frond (PI. II, 

 fig. 2), than those of the middle and base. The limits of the 

 divergence observed in the angles are 20° and 60°. The short 

 secondary veins are as close together as in Ch. vulgare. In 

 length and shape the meshes vary from rectangular to narrow- 

 lanceolate or linear ; sometimes, as PL II, fig. 4, from Studland, 

 not anastomosing throughout their entire length. In Ch. vulgare 

 the range of variation, in this as in other respects, is more circum- 

 scribed. 



The fossil, while closely resembling the recent Ch. vulgare, 

 seems to have been more variable in its growth, and differed 

 principally in the more amplexicaul attachment of the pinnae. 



ChrTjsodium Lanzaanum was described in 1858 by Visiani 

 from the Eocene of Monte Promina as Fortisia, a genus which he 

 founded for this and a closely allied species. In 1877 Saporta 

 announced the discovery of a Chrysodium from the Aquitanian 

 beds of Manosque in Provence •} — " Je ne puis m'empecher de 

 signaler * * * un tres beau Chrysodium, genre d'acrostichees, 

 dont une espcce encore incdite, recueillie aux environs de 

 Manosque, se rattache directement aux formes les plus nettement 

 tropicales." This Chrysodium from Manosque, of which nume- 

 rous pinnse are preserved on the surface of a large slab, is nearly 

 allied, Saporta informs me, like the Bournemouth plant, to Ch. 

 vulyare ; but the pinna3 are narrower, more lanceolate, and with a 

 more acute and attenuated apex, and the whole plant appears to 

 have been more slender j resembling in these respects the 

 Ilordwell specimens. He therefore thinks that the two can 

 hardly be identified as a single species. It is remarkable that it 

 was there associated with Lastraa Stiriaca, Osmiinda liynitum, 

 and Lyyodium Gaudini, as at Bournemouth and Bovey-Tracey, 

 and that witli tliese also occur at Manosque species of Pteris allied 

 to those of Bournemouth, Pteris pennceformis and P. iirophylla, 

 the latter only a variety of P. CRninycnsis. There is thus seen 

 to be a considerable resemblance in the Ferns from the two 

 localities, which arc supposed to differ in age sufficiently to 

 account for the slightly varying specific characters. Remains of 



1 ' La Nature, Revue des Sciences,' 5 annee. No. 'J24, p. 245, 15th 

 September, 1877. 



Fig. 11. — Chrysodium vulgare. 



