NO. 1862. FOSSIL FERNS FROM THE POTOMAC GROUP— BERRY. 319 



Pecopteris, sp., Nathorst, Denksckr. k. Akad. Wiss. Wien, vol. 57, 1890, p. 48, 



pi. 4, figs. 2-6. 

 Cladophlebis ungeri Ward in Fontaine, in Ward, Monogr. U. S. Geol. Surv., vol. 



48, 1906, pp. 228, 510, 538, pi. 65, figs, 15, 16.— Knowlton, in Diller, Bull. 



Geol. Soc. Amer., vol. 19, 1908, p. 386. 

 Pecopteris brevipennis Fontaine, Monogr. U. S. Geol. Sm-v., vol. 15, 1890, p. 86, 



pi. 21, figs. 1-3. — Fontaine, in Ward, Monogi*. U. S. Geol. Surv., vol. 48, 



1906, p. 510. 

 Pecopteris pachyphylla Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 88, 



pi. 26, figs. 4, 5. 



Description. — A satisfactory diagnosis is the one written by Pro- 

 fessor Fontaine for his Aspidium Dunkeri which will answer not only 

 for that material but for all of the other supposed species founded by 

 Fontame upon various fragments of CladopJilehis ungeri. It is as 

 follows : 



Frond bipinnate or tripinnate, arborescent; principal rachis stout and rigid; ulti- 

 mate pinnse alternate, short, linear-lanceolate; pinnules alternate or subopposite, 

 short, closely placed, narrowed at the base, cut more or less deeply into lobes or teeth 

 which are ovate or oblong, obtuse or subacute, very small, those of the fertile portions 

 of the frond standing nearly perpendicular to the rachis and having in each lobe or 

 pinnule a simple lateral nerve which bears a sonis on its summit, those of the sterile 

 and more common portions more obliquely placed, mostly subacute, with nerves 

 in each lobe that fork simply in the upper ones, and in the lower ones are composed of 

 a midnerve with alteiTiate simple branches; leaf-substance thick; sori very minute, 

 club-shaped or elliptical, visible distinctly only with the help of a lens, and present 

 only in the pinnules of the lower part of the pinnse, and mostly found on the lobes 

 toward the base of these. 



This species was described by Dunker in. 1846 from the Wealden of 

 Northern Germany as Pecopteris ungeri and Pecopteris poli/morpha. 

 Schimper in 1869 renamed the latter Pecopteris dwiikeri for the reason 

 that the specific name polymorpha had been used by Brongniart in 

 1828. Schenk two years later, with Dunker's original specimens 

 before him, announced that Dunker's ungeri and polymorpha were 

 synonymous. He did not, however, restore Dunker's name nor 

 has Seward done so iii his discussion (1894) of tliis species in the 

 "Wealden Flora." In accordance wdth the prevaiHng system of 

 nomenclature Dunker's original name must be used for this species, 

 and this proposal was made by Ward in 1906. Seward in 1894 referred 

 the species to the genus Cladophlebis and while the American material 

 available in the present treatment of this species is not as complete 

 as might be desired it furnishes some evidence regarding the fertile 

 fronds of still another species of Cladophlehis. The character of the 

 fertile material is rather vague and while it is clearly congeneric with 

 a number of other of Fontaine's species of Aspidium, it is hardly 

 sufficient evidence of their relationsliip with that modern genus. 



The present species is close to Cladophlehis hrowniana and is appar- 

 ently a cosmopolitan Lower Cretaceous type since indistinguishable 

 material occurs not only in the English and Continental Wealden 



