JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 95 



1844. Nilsonia compta (Phill.) Gopp.: Uebersicht d. Arbeiten d. Scliles. Ges. f. 



Vaterl. Kultur, 1843, p. 139. 

 1870. Pterozamites comptus (Phill.) Schimp.: Pal. Veg., Vol. II, p. 147. 



Several specimens of a plant were obtained from localities Nos. 7 

 and 19 that seem to be identical with the fossil called by Lindley and 

 Hiitton Pterophyllum comptum," which is now regarded as a Nilsonia. 

 The Oregon specimens, in the shape of their segments, agree best with 

 Schenk's figure of this species." The specimens are poorly preserved 

 and show only small portions of the leaves. The segments vary in 

 size. They are oblong in form, shghtly falcate and obtuse at the ends, 

 with the posterior margins of the ends more curved than the anterior, 

 so as to produce a narrowing at the ends. From distortion some of 

 them seem to be wider at their bases, but are not really so. The lateral 

 nerves are slender but distinct. They go off nearly at a right angle, 

 are parallel to one another, and single. They curve slightly forward 

 toward the ends of the leaves. The longer segments are 15 mm. in length, 

 but they vary in length and width. The average width is about 6 mm. 

 The smaller segments do not surpass 10 mm. in length and 4-5 mm. in 

 width. Some of the basal segments are abnormally wide, as if from 

 consolidation of two adjacent ones, but this is evidently not an essential 

 feature. This heteromorphous form in basal segments seems to be a 

 common feature in cycadaceous leaves segmented after the fashion of 

 Pterophyllum. Such segments are shown in PL XVII, Fig. 14. 



PL XVII, Fig. 11, shows the smaller form of the Oregon plant, 

 and Fig. 12 a single segment enlarged. Fig. 13 represents the larger 

 form. This specimen is somewhat distorted in the ends of the segments, 

 so that they appear wider at their bases. Fig. 14 represents a fragment 

 from the basal part of a leaf. 



fflFoss. Fl. Gt. Brit., Vol. I, pp. 187-190, pi. Ixvi. . 



^Schenk, Pflanzliche Versteinerungen aus Richthoten's China, Vol. IV, p. 262, pi. liv, fig. 2b. 



