DESCRIPTION OF THE SPECIES. 195 



margin on the upper or under surface of the stem, either attenuated 

 towards the base or abruptly rounded off there, at their ends acute or 

 subacute ; nerves several, coalescing at base to form a footstalk, forking 

 immediately at the base or a short distance above, then approximately 

 ])arallel to near the tips of the leaves, where they are somewhat crowded 

 together, but do not converge to a union, ending in or near the extremity. 



This fine genus is one of the most largely developed and characteristic 

 forms of the Potomac flora, furnishing a very important and widely diffused 

 type. The single leaves and unbranched leafy twigs are so much like the 

 cycad genus Podo^amiten, that when they were first found I took them to 

 ])e forms of that genus, but later so many specimens were found showing 

 unquestionable coniferous characters, that I found myself, contrary to my 

 preconceived notions, compelled to regard the plants as coniferous. 



This genus is so much like the 2\agcia section of I'odocarpus, that I have 

 felt considerable hesitation in making it a distinct genus. It may be a 

 question whether or not some of the species hitherto described as Podo- 

 zamites in other formations besides the Potomac should be regarded as be- 

 longing to Xa()eiopsis. In the absence of branching twigs it is not always 

 easy to distinguish these plants from Podozamites. In the leaves of this 

 plant, however, the nerves do not converge and unite in the tips as in Podo- 

 zamites. This is the only feature which will distinguish detached leaves 

 of the two genera. 



I am strongly inclined to think that Podozamites Emmonsi, Newberry, 

 from the Rluetic of North Carolina and Virginia, as well as Podozamites 

 tenuistriatus, from the same formation, belong to Nageiopsis. 



Nagkiopsis longifolia, sp. nov. 



Plate LXXV, Fig. 1 ; Platr LXXVI, Figs, -2-0; Plate LXXVII, Figs. 1, 2; Plate LXXVIII, Figs. 1-5; 

 Plate LXXIX. Fig. 7 ; Plat<> LXXXV, Figs. 1, -2, 8, '.t. 



Leafy twigs very large, with stout woody stems sometimes l'"' and 

 over thick ; leaves strap-shaped, narrowed at the base, attached by a short, 

 slightly twisted petiole most commonly to the margin of the stem, rarely 

 within it on the upper and lower face, acute or subacute, and gradually 

 narrowed towards the tips, varying in width and length ; maximum length 



