H KASSIC FLOUA OF DOl'CiLAS COrNTY, OKE(;. 



98 



proportion to tlunr wi.lth thrv arr .>xtra..nlinanlv lon^. Ih.v nu.st 

 have iK^en pc>n,h.lous. Tlu>y ran^c in wi.lth tVon. 2 nun. ..r o nun. to 

 10 nun Vrrv f.-w attain tl.r latter wi.ltln Most -f tl.em are r.un 

 5-7 nun wi.le. Tlu-ir len.^tli is unknown. U tnav l.e estimate.l hy 

 (he fac^t that o,u> specunen was foun<l 12.5 nun. l....g, widening grac u- 

 allv until it attahx.l the width of 7 .n,n. rsuallv the change m width 

 is impereeptihle h. short fraf^ntents, and thev look like blades of gfass. 

 The midrib, when visible, is in the hn-er leavs pn.port.onallv .,uite 

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

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

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

 of a lens This is on account of the thick leaf substance, whu-h ditters 

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

 The leaf shows no trace of segmentation, and is ivmarkably free trom 

 accidental laceration, imitating segmentation. , , ., „ , , 



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

 Yokovama 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. , t^ • 



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

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

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

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

 The' specimens represented in Figs. 2 and 3 both occ-ur on the same 

 rock fragment with the plant depicted in lug. 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 

 occurring smaller leaves, and Fig. 5 shows a portion of this enlarged. 

 Fi<r 6 sliows a fragment of one of the largest leaves, a kind not often 

 found This in width approaches the smaller forms of Nihoma on- 

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



enlarged in Fig. 7. , ,. . x- o ,. i io 



The plant is exceedingly abundant at localities Nos. 2, (., and IJ, 



thickly covering faces of the rock. It is very al)undant at No. 4, and 

 is also found at Nos. 7 and 15. 



"^-o^-a,n^ra.ssk. plants fron, Ka,a, oto.: -Tourn. Cll. In.,,. Univor. .Tapan. Vol. HI, P.. I, pp. 41-42. 

 pi. X, figs. 2b, 11-14. 



