DESCRIPTION OF THE SPECIES. 109 



from near Potomac Run, but the difference is not sufficient to separate 

 them. Figure 14 give.s, magnified, a comj)lete leaf corresponding to those 

 of Fig. 7, Init more complete than any found on that specimen. 



AcROSTIcnoPTEKlS CYCLOI'TEROIDKS, Sp. UOV. 

 riato XCIV, Fig. r*. 



Piiuiules rounded, fan- shaped, cyclopteris-like in form, divided to the 

 base into three principal lacini;e, which in turn are subdivided at different 

 distances from the base into subordinate lobes; lacinioc all oblong, diverg- 

 ing flabellately, the principal ones cuneate at base ; they end in obtuse 

 oblong teeth, which are quite narrow ; nerves obscure, but, as in the gen- 

 eric description, dividing repeatedly in a dichotomous manner from the 

 base and diverging flabellately, so that the ultimate branches end in the 

 teeth; fertile forms not seen. 



Locality : Fishing hut above Dutch Gap Canal ; rare. 



Several specimens of this plant were found, but they appear onl)' in 

 the form of detached pinnules, one of the largest of which 1 have figured. 

 It has a small bit of the rachis still attached. This plant shows a numbei- 

 of detached pinnules lying as if they had fallen from the same plant. It 

 is more like Bakropsis than any of the species of Acroetichopteris, and in its 

 fragmentary state, with fructification not shown, it may Ijelong to that 

 genus of conifers. 



ASPLENIUM L. 



The genus Asplenium found by Heer so abundant in the Jurassic flora 

 of Siberia is not determined positively in the Potomac flora. The species 

 described below — A. duhium — quite possibly may belong to the tribe of 

 the Aspidiece, being found in the section with oblong sori as in Fadyenia. 



Asplenium dluiim, sp. nov. 



Plate X. Fill. U. 



Frond bipinnate or tripinnate ; jjinnules oblong, subacute, separate to 

 the base, alternate, nearly at right angles with the rachis ; nerves furcate, 

 bearing the sori on the end of the upper branch, sori elliptical, in a row 



