TO JUNCTION OF GRAND AND GREEN RIVERS. 145 



PTEROPHYLLUM EOBUSTUM, Newb. 



Plato VI, tig. 7. 







Leaf large, G inches or more in width; pinna 1 strap-shaped, 3 inches in length; 

 buses expanded and* coalescing; summit truncated or abruptly rounded; nervation 

 delicate; nerves simple, parallel with the border of the pinna?,. 



Two specimens of this singular plant are contained in the collection made by Mr. 

 Remond, both imperfect, but both exhibiting the same characters. These are so pecul- 

 iar that, without the evidence of ttco specimens, I would have said we had here simply 

 a frond of Tcemopteris torn into strips, with an accidental but striking regularity. It 

 seems hardly probable, however, though not impossible, that we should find in this 

 small collection two fronds torn in precisely the same way. Besides this, the curvature 

 of the sides of the divisions, where they coalesce at the base, is almost too regular to 

 be the result of accident. They are also too uniform in width to be the effect of 

 mechanical force. I have thought best, therefore, to describe this provisionally as a 

 distinct species of PterophyUum. 



Formation and locality. Triassic strata ; Los Bronces, Sonora. 



PODOZAMITES CRASSIFOLIA, Newl). 

 Plate VI, fig. 10. 



Plant large and strong; pinna3 long-elliptical or spatulate in form, thick and 

 coriaceous; nervation strong, but somewhat obscured by the thickness of the paren- 

 chyma; nerves parallel with the border, converging at both extremities of the pinnae; 

 a more distinct nerve traverses the central line. 



Only detached pinme of this plant are contained in the collection made by Mr. 

 Remond, but of these there are quite a number. By their large size and thickness, 

 they are greatly different from those of any species of Podozamites hitherto described, 

 and the distinct median nerve which they show presents a feature not common, if 

 even known, in this genus. It is, therefore, possible that more complete specimens 

 will -show it to have characters which should be given generic value. 



Formation and locality. Triassic strata; Los Bronces, Sonora. 



ALETHOPTEKIS WHITNEYI, Newb. 



Plate VII, figs. 1,1", I 1 '. 



Frond pinnate or bipinnate ; pinnules of lower portion large, 2-3 inches long, 

 narrowed above, broad below ; the lower half of the base attached to, and decurrent 

 on, the rachis ; the upper half detached and snbcordate ; upper pinnules shorter, be- 

 coming at last elliptical and even orbicular ; nervation crowded ; midrib strong ; lat- 

 eral nerves fine and numerous, given off at nearly a right angle, simple or once forked. 



The specimens of this plant are too fragmentary and imperfect to permit a full 



and complete description of it. Enough remains, however, to show that it was a 



strongly-marked species, and one quite distinct from any before described from this 



horizon. That portion of the frond contained in the collection made by Mr. Remond 



19 SP 



