JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 57 



To jvidge from the specimens, the plant shows a marked tendency 

 to fructification, for most of them are fertile parts. It is probably a 

 new species. The sterile entire pinnules resemble those of Heer's Dick- 

 sonia gracilis," from the Jurassic of Asia, but the ultimate pinna; are 

 shorter, and Heer's plant lacks the heteromorphous feature in the 



pinnules. 



Heer calls attention to the resemblance of his plant to the Scle- 

 ropteris Pomelii of Saporta, from the Jurassic of France. This resem- 

 blance exists, but it is not sufficient to justify identifying the Oregon 

 form with Saporta's fossil. No fructification exists on either of these 

 previously described fossils, and in view of the predominance of it in 

 the Oregon fossils it is not likely that it would be wanting in the for- 

 mer if they are identical with the latter. In shape and size the sori 

 of Dicksonia oregonensis agree pretty well with those of Heer's Dick- 

 sonia clavipes," from the Jurassic of Siberia, but the fertile pinnules 

 are not, as in that plant, contracted to stalks. So many specimens 

 of the plant now in question were obtained that a pretty full repre- 

 sentation of it may be given by selecting parts from different positions 

 on the compound pinnae. This is necessary because of the small size 

 of the fragments that are preserved. 



PL VI, Fig. 3, represents a portion of a penultimate pinna with 

 several attached ultimate pinnae, as well as several unattached ones, 

 that apparently were once attached. This is the only specimen in hand 

 that is credited to Mr. Todd's collections. It presents the upper sur- 

 face of the plant uppermost and shows the sori as they appear in such 

 a case. When this specimen was the only one available, I was led to 

 regard it as Aspidium monocarpum, a fern found in the Lower Creta- 

 ceous of Great Falls, Mont. This is the specimen referred to as 

 Dryojoteris monocarpa by Professor Ward in the paper quoted above 

 (p. 369).'' Specimens showing the same character are not uncommon 

 in the collections made since that of Mr. Todd, and they show that the 

 plant is Dicksonia oregonensis. PI. VI, Fig. 4, shows a single pinnule 



"Flor. Foss. Arct., Vol. IV, Pt. II (Beitriige zur Jura-Flora Ostsibiriens und des Amurlandes), p. 92, 

 pi. xvii, fig. 3. 



bOp. cit., pp. 33-34, pi. ii, fig. 7. 



f The genus name Dryopteris (Adanson, 1763) has priority over Aspidium (Swartz, 1800) by twenty- 

 seven year^. Dr. Knowlton referred Professor Fontaine's species {monocarpa) to the former genus in his 

 Catalogue of the Cretaceous and Tertiary Plants of North America (Bull. U. S. Geol. Survey No. 152, 1898), 

 p. 92.— L. F. W. 



