74 MESOZOIC FLORAS OF UNITED STATES. 



crenate margins. In each lobe there is a parent nerve that spUts up into 

 branches. It may give off one or more pairs of lateral nerves that go off 

 very obliquely. The nerve group has a flabellate character. No fruc- 

 tification was found. The plant is probably a new species. It resembles 

 very much the Pecopteris obtusifolia (Murray) Lindlpy & Hutton" and 

 may be the Oregon representative of it. In the English fossil, however, 

 the ultimate pinnae, corresponding to the pinnules of this plant, are much 

 longer, and fructification was found. Phillips identifies the species of 

 Lindley & Hutton with his Pecopteris exilis.^ Seward regards Pecopteris 

 exilis as a Klukia.'' 



PL XI, Fig. 13, shows the specimen natural size, and Figs. 14 and 

 15 give enlargements to show details of nerves. 



Genus SCLEROPTERIS Saporta. 



SCLEROPTERIS OEEGONENSIS Foiltalne 11. sp. 



PI. XII, Figs. 1-3. 



A single specimen of a fern was found of pretty good size and fairh^ 

 wel preserved at locality No. 19. According to Saporta's diagnosis 

 of the genus Scleropteris,'' this genus clearly includes the plant in ques- 

 tion. The specimen shows a considerable portion of a penultimate 

 pinna, which bears fragments of a number of ultimate pinnse, with pin- 

 nules. The ultimate pinnse are very short, the longest of them not 

 surpassing about 3 cm. The rachis is narrowly winged. The pinnules 

 are rigid and have a very thick leaf substance that conceals the nerves, 

 so that they generally are difficult to make out. The lowest pinnule 

 on the upper side of the rachis is oblong, obtuse, and larger than the 

 rest. It is crenate on the margins or has shallow obtuse teeth. The 

 other, and normal pinnules, are not more than 5 mm. long and about 

 3 mm. wide. They are entire, oblong-elliptic in form, with very obtuse 

 tips, and go off obliquely from the rachis, with a slight inclination toward 

 the ends of the^ pinnae. They are decurrent, forming the wing. All 

 the pinnules are constricted at base. The nerves are immersed appa- 

 rent y in the leaf substance. They are composed of a parent nerve 



aFoss. Fl. Gt. Brit., Vol. Ill, pp. 15-16, pi. chiii, fig. 1. 



fiGeolog}' of Yorkshire, 3d. ed., p. 210, pi. viii, fig. 16. 



'•Jurassic Plants in the Manchester Museum, p. -l; Jur. Fl. Yorkshire Coast, p. 130. 



('Pal. Franc^aise, Plantes Jurassiques, Vol. I, pp. 364-365. 



