Fossil. Vegetation of America. ~ 377 
itis evident much remains to be done, both in. the discovery 
of new species and in deciding on synonyms. : 
The late acute and very philosophical investigations by 
Presl, and by J. Smith, of Kew Garden, of the ferns of the 
present day, and the consequent arrangement of them by 
these gentlemen into divisions, dependent on the combination 
and position of the veins, as well as on the mode of fructifica- 
tion, will render great assistance to the student of this portion 
of the fossil flora ; for, as yet, the venation must hold tlie first 
Place in deciding on its arrangement. The outlines of these 
characters have been beautifully developed by Brongniart: in 
his above work, and although Géppert has delineated many 
instances of fossil fructifications, and, with Unger, introduced 
several judicious modifications of Brongniart’s views, the vena- 
tion must still retain its weight. Sternberg’s great work on this 
subject I have not seen. The fern recently brought by Mr. 
Cuming from the Island of Luzon, Dryostachyum (J. Smith,) 
resembles, in the venation of its sterile frond, the fossil genus 
hropteris of Brongniart, while its fertile frond may almost 
be identified, in outline, with the fossil PAlebopteris propin- 
4, of the same author ; rendering nearly certain the proba- 
bility, which he suggested, that these two fossils are the sterile 
and fertile fronds of one species.  Clathropteris, also, resem- 
bles, in venation, the sterile frond of Aglaomorpha (Psygmi- 
Nn Presl,) a recent fern ; but the fertile frond differs some- - 
What from the form of Phlebopteris. — 
The figure of Woodwardia floridana (Schk.) given by 
Goppert, Syst., tab. XXI., does not contain the venation now 
considered characteristic of this fern; his division Woodward- 
Hes, among fossils, will therefore probably not stand. His 
figures of these latter, also, exhibit the same deficiency. m 
The venation and position of the sori in Hemitelites, Góp- 
Pert, does not agree with Hemitelia, as now restricted by Pres! 
to H. capensis. The group of recent Cyatheacec, when 
Moperly arranged, so as to exhibit the full value of its vena- 
?; Compared with the fluctuating character of its indusium, 
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