418 PALEONTOLOGY OF OHIO. 



In all the preceding four species of Megalopteris the first forking of the 

 nervules of the pinnae is often obscure, not showing distinctly except 

 where the parenchyma has been partially removed. 



Locality same as previous species. 



Archeopteris stricta (sp. nov.). 



Plate 49, figs. 2 and 2a. 



Frond bi-pinnate. Rachis comparatively thick, straight, regularly 

 and thinly striate. Pinnae alternate, somewhat closely set, growing out 

 of rachis atan angle with it of 70° to 75°, rarely as small as 45°. Pin- 

 nules alternate, bblanceolate, obtuse, decurring on the narrow rachis, dis- 

 connected to the base, with a strong nerve dividing near the base into 

 three to five branches, which themselves fork once or twice before reach- 

 ing the margin. 



This beautiful fern is allied to Cydopteris Jacksoni, Dawson, from the 

 Devonian, but is in all respects a smaller and more delicate plant. It 

 differs from it not only in its much shorter pinnae, and in the less acute 

 angle made by them with the rachis, but in having its pinnules discon- 

 nected to the base, not imbricated. The nervation is also quite different. 

 In C. Jacksoni the veins are slightly curved and nearly parallel, while 

 in this species they are once or twice dichotomous from near the base, 

 with branches diverging and fan-like. 



It is still more like C. Roemeriana, Goepp., but is a more delicate 

 species, with shorter, open, straight pinnse proceeding from rachis at a 

 greater angle, with pinnules shorter and less distant, with one strong 

 branching nerve instead of several, and a regularly thinly striated rachis. 



Dr. Dawson suggests Archasopteris as the generic name of this group, in 

 preference to Palmopteris, Sch., which is preoccupied. Fig. 2 shows the 

 nervation and leaf magnified. 



Locality same as the last. 



ORTHOGONIOPTERIS (genus nov.), Andrews. 



Frond simply pinnate. Pinnae alternate, lanceolate, or oblong-linear, 

 rounded and tapering to an acute point, entire or undulate, enlarged and 

 decurrent on lower side, rounded on the upper to the middle nerve, and 

 joining it a little above the point of its attachment to the rachis. Me- 

 dial nerve prominent, thick, ascending to the apex. Nervules very fine 



