92 MKSOZOIC FLORAS OF rXITFI) STATFS. 



NiLsoNiA OKiEXTALis MiNoK Foiilaiiio 11. var. 

 PI. XVI, Fi<r.s. i()-i;j. 



As a rule, the leaves of the j^lant here called Xilsnnid oriciitdlii^ 

 miliar ai'e decidedly smallei- than those of the type, hut the largest nia_y 

 (^(jual the smallest of the original species — that is, they may attain 

 the witlth of 2 cm. A nearly entire leaf of average size was found, 

 which shows that the variety miiwr was about 8 cm. long and 15 nma. 

 wide. The form was prol)al)ly olilong elliptical, with subacute tips. 

 The lateral nerves are proportionally stronger than those of the species 

 and somewhat closer, being two to the millimeter, otherwise they are 

 as in the species. Heer, on pi. i\. tig. 5, of the work quoted (supra, 

 p. 151), gives a form that in shape and size reseml:)les the variety now 

 in cjuestion. Fig. 8 of the same plate may belong to this variety, for 

 Heer indicates that the plant represented in it antl in fig. 5 had closer 

 nerves than the type. 



PI. XVI, Fig. 10, gives a nearly entire medium-sized leaf, and Fig. 

 11 sliows the summit of this enlarged. Fig. 12 shows the greater part 

 of one of the smallest leaves. Fig. 13 represents a fragment of the 

 middle part of one of the largest leaves. 



The plant occurs most commonly at locality No. 7, and is also 

 found at localities Nos. 1, 2, 6, 8, and 19. 



NiLSONiA PARVULA (Hccr) Foiitiilne n. comb. 



PI. XVII, Figs. 17. 



1876. Tseniopteris parvula Heer: Fl. Foss. Arct., Vol. IV, Pt. II, p. 9S, pi. xxi, 

 figs. 5, 5b. 



Heer has described from the Jurassic of Siberia a small tjeniop- 

 leroid plant with the name Tieniopkris pnnmla, which is almost cer- 

 tainly the same as a plant that is very abundant at some of the Oregon 

 localities. Heer obtained only a single small l)it of a leaf 5 mm. wide, 

 and naturally could not determine its true nature. The large number 

 of well-preserved specimens from Oregon show that the fossil is a 

 Xilsonia, iielonging to the unsegmented kind. A midrib is sometimes 

 shown, and sometimes its place is taken by the cord characteristic of 

 the Nilsonias. This is according as the under or upper surface of the 

 plant is presented uppermost. The leaves vary much in width. In 



