JURASSIC FLORA OF DOUCiLAS (^OUNTY, OREG. 63 



author. But as theix' is no ijood moans of scparatius them, and as, on 

 the whole, they agree hotter with Tlnjr^ojiUris Mim-aijana, I place them 



in that species. 



The forms united under this si)ecies occiu- with several inii)rints 



at localities Nos. 2, 7, and 19. 



Family POLYPODIACE^. 



Genus POLYPODIIIM l.innaus. 



POLYPODIUM OREGONENSE Folltaim- 11. sp. 



PI. VIII, Fi,i;s. 12-15; PL IX; PI. X, Figs. 1-7. 



This plant was prolialily arborescent. The pmnse were long and 

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

 least tripiiuaate subdivision, but they are evidently parts of much 

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

 to their position on the pinmie of various orders. They pass from entire 

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

 or crenate margins, to those with serrately dentate and lol)ed margins, 

 and finally into ultimate pinna^. 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 pinna^. They are sep- 

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

 row wing. They are attached l)y 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 midulate 

 or crenate margins have lateral nerves, mostl>' 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 occurring 

 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 becoming 

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



