Maryland Geological Survey 365 



the material is indecisive and the forms identified by Professor Fontaine 

 (1906) as this species from the Mt. Vernon beds, which are of Patapsco 

 age, prove to be identical with what Professor Ward named Scleropteris 

 vernonensis, which in turn is not a Scleropteris, but by the character of 

 its fertile fronds is related to Dichsonia. 



Occurrence. — Patuxent Formation. Near Potomac Run, Virginia. 

 Patapsco Formation. Near Brooke (?), Virginia. 



Collection. — U. S. National Museum. 



Genus ASPLENIOPTERIS Fontaine 

 [Mon. U. S. Geol. Surv., vol. xv, 1890, p. 117] 



This genus was characterized in the following terms by its describer : 

 "Frond bipinnate or tripinnatifid ; pinnules linear-lanceolate, or ob- 

 long, acute to obtuse, lobed or toothed, sori proportionally very large, 

 elongate to narrowly elliptical, in a row on each side of the midrib, one 

 in each lobe or tooth, inserted on thick supports or segments, which 

 represent the transformed segments or lobes, placed on the anterior mar- 

 gin of these, and running down nearly their entire length.'^ 



The foregoing diagnosis unduly emphasizes the thickening of the fer- 

 tile lobes, which are but little, if any, thickened. Professor Fontaine 

 compares the genus with Dichsonia clavipes Heer, but there is little in 

 common between the two. The Potomac forms are very poorly preserved, 

 and in some respects they suggest the fertile parts of Onycliiopsis. How- 

 ever, after a thorough canvas of the Filicales, the writer has decided to 

 retain the genus in the tribe Aspleniege. No additional soral characters 

 coiTld be made out and no traces of spores were found. 



AsPLENioPTERis piNNATiFiDA F.ontaine 

 Plate XXVIII, Figs. 5, 6 



Aspleniopteris pinnatiflda Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 

 1889, p. 118, pi. xxii, figs. 1-3, 6, 7 (non Fontaine 1894, 1896). 



Description. — " Frond tripinnatifid ; rachis of the primary pinna or 

 of the frond very stout, rigid, and straight; pinnae or pinnules alternate, 

 varying much in length according to position, with strong, rigid rachises ; 



