JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 55 



abundant. The specimens are generall}' very fragmentary, and, what is 

 noteworthy, the parts preserved are often in a good state of preservation 

 in that the epidermal tissue is intact, and the plant substance gives a 

 black carbonaceous film on the rock. The parts do not seem to have 

 suffered much from maceration due to long floating in water, hence the 

 fragmentary state must be produced by some other cause. The coniferous 

 fossils also show a great comminution of parts, with a good preservation 

 of the plant substance. The cycads do not show so extensive a laceration, 

 although they, too, are much broken, while the parts that are shown are 

 wonderfully well preserved. 



Family CYATHEACE^." 

 Genus DICKSONL^ L'Heiitier. 

 DicKSONiA oREGONENSis Fontaine n. sp. 

 PI. VI, Figs. 3-9; PI. VII. 

 1898. Dryopteris moiiocarpa (Font.) Kn.: Bull. U. S. Geol. Surv., No. 152, p. 92. 

 1900. Dryopteris monocarpa (Font.) Kn. Ward: Twentieth Ann. Rep. U. S. Geol. 

 Surv., 1898-99, Pt. II, p. 369. 

 This plant was probably arborescent. Both fertile and sterile forms 

 were obtained. Most of the specimens show fertile forms. The largest 

 specimens seen with attached pinna; give no more than a tripinnate 

 division but these were evidently fragments of much larger compound 

 pinnae. Fragments of a rachis not showing attached pinna?, but so asso- 

 ciated with this fern as to indicate clearly that they belong to it, were 

 obtained that are 8 mm. wide. The ultimate pinna? are very short, not 

 surpassing 45 mm. in length. The pinnules with entire margins, such as 

 are found in the upper portion of the compound pinna? and in terminal 

 parts of the subordinate pinna?, are quite small, being not more than 3-4 

 mm. long and 2-3 mm. wide. They are narrowed toward the base and 

 elliptical in form. They are attached by this narrowed base so as to make 

 a small angle with the rachis, and are decurrent, forming a very narrow 

 wing. The basal pinnule on the upper side of the ultimate pinna is larger 

 than the rest and is more incised, having undulate or dentate margins 



"When my first paper was written the part of Engler and Prantl's system containing the Pteridophyta 

 was as yet unpublished. It has since been completed, and their subdivisions into families will be followed 

 in the present paper. — L. F. W. 



