JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 63 



author. But as there is no good means of separating them, and as, on 

 the whole, they agree better with Thyrsopteris Murrayana, I place them 

 in that species. 



The forms united under this species occur with several imprints 

 at localities Nos. 2, 7, and 19. 



Family POLYPODIACEiE. 



Genus PULYPODIUM Linnseus. 



PoLYPODiUM OREGONENSE Fontaine n. sp. 



PI. VIII, Figs. 12-15; PI. IX; PI. X, Figs. 1-7. 



This plant was probably arborescent. The pinnae were long and 

 wide-spreading, with rigid rachises. The fragments obtained show at 

 least tripinnate subdivision, but they are evidently parts of much 

 larger portions. The pinnules show a good deal of variation, according 

 to their position on the pinnae of various orders. The}^ pass from entire 

 pinnules in the upper and terminal parts, through pinnules with undulate 

 or crenate margins, to those with serrately dentate and lobed margins, 

 and finally into ultimate pinnae. The entire pinnules are more or less 

 triangular in form, with broad bases, and are falcate, with acute tips 

 that are directed toward ends of the ultimate pinnae. They are sep- 

 arate nearly to the base and decurrent on the lower side to form a nar- 

 row wing. They are attached by the entire base. The epidermis is 

 firm and durable, so that parts of the plants are often well preserved. 

 The nerves consist of a parent nerve that is inserted near the base of 

 the pinnule and goes off at a small angle. This is forked, with the 

 posterior branch forking again, and all- the branches curving toward 

 the anterior margin of the pinnule, or it may be only once forked in the 

 more united pinnules in terminal parts. The pinnules with undulate 

 or crenate margins have lateral nerves, mostly forked at their tips or 

 else simple. In the serrately dentate and lobed pinnules the lateral 

 nerves, one for each incision, are once forked, the forking occuiTing 

 more deeply as the incising is deeper. The simple lateral nerves and 

 the parts below the forking in the forked ones are parallel to one another. 

 All the nerves are remote and distinct. The pinnules, in JDecoming 

 incised, change their form, being oblong, with little or no falcation. 



