258 THE POTOMAC OR YOUNGER MESDZOIC FLORA. 



slender midnerve, subfalcate, narrowly oblong to narrowly elliptical, 

 decurrent, with the tips slightly divergent and incurved, those on the 

 upper and lower surfaces of the stems (facial ones) close appressed, with 

 no visible midrib, oblong to elliptical, obtuse to subacute, remote. 



Localities: Fredericksburg; 72d mile-post, near Brooke. 



This plant is not very rare at Fredericksburg, and is very conmion at 

 the 72d mile-post, where it occurs in numerous fragments in the confusedly 

 mixed sand and clay. The peculiar mode of branching reminds one of 

 Heer's Sequoia concinna from the Atane beds of Greenland, but the leaves, 

 although of the same general character as those of S. concinna, are more 

 closely placed and not so long and slender. 



Sphenolepidium dentifolium, sp. nov. 



Plato CXXVII, Figs. 3, 4 ; Plate CXXVIII, Figs. 2-6; Plate CXXIX.Fig.S; Plate CXXX. Figs.4-f., 10 



Stems branching freely, with long, slender, rigid, alternate twigs, that 

 are obliquely attached; leaves ovate, oblong, or elliptical, thick, short, 

 acutely dentate in form, obliquely placed, decurrent, and united at base in 

 the same plane, with no leaves apparently on the upper and lower faces of 

 the twigs ; midnerve distinct and often strong. 



Locality : Fredericksburg. 



This plant is one of the most common conifers at Fredericksburg. 

 It is mucli like Sequoia Couttsia; but the thick, short, tooth-shaped leaves 

 differ from those of this Sequoia. PI. CXXX, Fig. 6, and PI. CXXVII, 

 Fig. 4, give two twigs which show on their tips two lateral undeveloped 

 leaf-buds and a terminal partially developed one. The ultimate twigs on 

 most of the specimens are placed rather remotely and irregularly, showing 

 a tendency to a fastigiate grouping, but in PI. CXXVIII, Fig 5, they are 

 closely placed at regular. intervals and in a pinnate manner. The plant 

 reminds one of some forms of Sphenopteris Mantelli. 



Sphenolepidium eecurvifolium, sp. nov. 



Plate CXXVII, Fig. 2 ; Plate CXXX, Figs. 2, 7. 



Branches and branchlets slender and very long, ultimate branches 

 inserted very obliquely and at irregular intervals, strongly turned upwards; 



