JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 93 



proportion to their width they are extraordinarily long. They must 

 have been pendulous. They range in width from 2 mm. or 3 mm. to 

 10 mm. Very few attain the latter width. Most of them are from 

 5-7 mm. wide. Their length is unknown. It may be estimated by 

 the fact that one specimen was found 125 mm. long, widening gradu- 

 ally until it attained the width of 7 mm. Usually the change in width 

 is imperceptible in short fragments, and they look like blades of grass. 

 The midrib, when visible, is in the larger leaves proportionally quite 

 wide and flat. In all it is proportionally strong. The lateral nerves 

 are of the usual kind in the entire Nilsonias, and they are in this species 

 well defined, but are too fine to be seen in most cases without the help 

 of a lens. This is on account of the thick leaf substance, which differs 

 in that respect from N. orientalis. None of them were seen to fork. 

 The leaf shows no trace of segmentation, and is remarkably free from 

 accidental laceration, imitating segmentation. 



The wider forms of this plant much resemble the fossil called by 

 Yokoyama Nilsonia ozoana," but the nerves are not strictly at right 

 angles and are stronger. Besides, there is no possibility of separating 

 them from the narrower forms. 



PI. XVII, Fig. 1, represents the longest specimen found. It gives 

 a good idea of the extreme slenderness of the leaves, for at its widest 

 end it is only 7 mm. wide. It is a portion of what was a much longer 

 leaf, which probably did not have anywhere a width much above 7 mm. 

 The specimens represented in Figs. 2 and 3 both occur on the same 

 rock fragment with the plant depicted in Fig. 1. In Fig. 2 a fragment 

 of medium size is represented. Fig. 3 gives a small portion of one of 

 the narrowest leaves. Fig. 4 gives a portion of one of the commonly 

 occiu-ring smaller leaves, and Fig. 5 shows a portion of this enlarged. 

 Fig. 6 shows a fragment of one of the largest leaves, a kind not often 

 found. This in width approaches the smaller forms of Nilsonia ori- 

 entalis minor, but is a much longer leaf. A portion of this is shown 

 enlarged in Fig. 7. 



The plant is exceedingly abundant at locahties Nos. 2, 6, and 19, 

 thickly covering faces of the rock. It is very abundant at No. 4, and 

 is also found at Nos. 7 and 15. 



"Yokoyama, Jurassic, plants from Kaga, etc.: Joum. Coll. Imp. Univer. Japan, Vol. Ill, Pt. I, pp. 41-42, 

 pl.x, figs. 2b, 11-14. 



