NO. 1862. FOSSIL PERM'S FROM THE POTOMAC GROUP— BERRY. 309 



roesserti} Certain specimens of the Jurassic species CladojpTiIehis 

 lohifolia show that the sporangia in tliis species were apparently 

 borne in semicircular pocket-hks depressions on the edges of the 

 fertile segments^ wliile the fructifications of CladojMehis denticulata 

 are in the form of narrow oblong sori parallel wdth tne secondary 

 veins and are compared by Seward^ with the modern forms Asplenium 

 lugubre and Phegopteris decussata. 



In liis latest utterance on tliis subject Professor Seward says that 

 ''there are fairly good grounds for the assertion that some at least of 

 the fronds described under tliis name are those of OsmundaceaB." * 



Zeiller has recently described a species from the Wealden of Peru 

 wliicli he considers identical with, or very close to, Cladophlehis 

 hronmiana in which the sporangia are biseriate, oval, and annulate as 

 in the Scliizaeacea?. These are said to be very Uke those of the 

 Jurassic genus Klukia of Raciborski.^ 



In the Potomac flora® we find that 14 so-caUed species of Aspidium 

 Swartz (Dryopteris Adanson), mostly fertile fronds, were described 

 by Fontaine in 1890. These showed mostly large elhptical or reni- 

 forni sori in rows on each side of the midvein and located generally 

 on the distal branch of a furcate vein and usually wanting in the 

 apical part of the pinnule. These were compared by tliis author with 

 modern species of Aspidium, Cystopteris, Polystichum, and Didy- 

 moclilaena. The preservation is not of the best, the matrix being 

 coarse, and Fontaine's figures are largely ideahzed. It has seemed 

 remarkable that the fronds of Dryopteris in the Potomac beds were 

 almost always fertile, wliile those of Cladophlehis, in intimate associ- 

 ation with them, were invariably sterile. 



By careful comparison it has been possible to correlate the fertile 

 specimens described as Dryopteris \vitli the sterile Cladophlehis fronds of 

 the same species in five of the types which are represented in the Poto- 

 mac flora by sterile and fertile fronds, and the presumption is strong, 

 although unverified, that the remaining Dryopteris forms represent 

 fertile fronds of Cladophlehis. Wliile the foregoing facts are not in 

 unison in regard to the systematic position of Cladophlehis, they all 

 point to the inclusion of the following American species in the family 

 Polypodiaceae or in what represented this family in Lower Cretaceous 

 times, and cast doubt upon Raciborski's suggestion that Cladophlehis 

 denticulata and other species of the same genus were the sterile fronds* 

 of osmundaceous ferns. It is quite possible that ferns of more than 

 one subfamily of the Polypodiaceae, or indeed of other famihes, are 



1 Schenk, Flora Foss., Grenz. Keup. Lias, 1867, p. 51, pi. 7, figs. 7, 7a. 



2 Seward, Jurassic Flora, pt. 1, 1900, p. 23. 



3 Idem, p. 141. 



« Seward, Fossil Plants, vol. 2, 1910, p. 345. 



6 ZeiUer, Comptes Rendus, vol. 150, 1910, p. 1488. 



• Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, pp. 93-104. 



