JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 



143 



known by Richthofen from China exist in the Oregon flora. These will 

 be noticed before taking up the plants common to Oregon, Yorkshire, 

 and eastern Siberia. PterophyUum Nathorsti and P. co7itiguum-ha.\e, as 

 yet, been found only in Oregon and in the Kwei-tshou beds of China. 

 Schenk thinks that they can not l^e older than Lower Jurassic. As these 

 strata, according to Schenk, contain Podozamites lanceolatus and Nilsonia 

 compta, they are most likely Lower Oolite in age. 



The Oregon strata have in common with the Kaga strata of Japan 

 Nilsonia nipponensis. Yokoyama regards the Kaga strata as- Lower 

 Oolite. 



The Oregon strata have in common with those of Yorkshire the 

 following species, some of which are highly characteristic of the Yorkshire 

 Lower Oolite: 



\. Cladophlebis denticulata. 



2. Cladophlebis haiburnensis. 



3. Thyrsopteris Murrayana. 



4. Ruffordia Gopperti. 



5. Tseniopteris major. 



6. Tseniopteris vittata. 



7. Sagenopteris paucifolia. 



8. Ptilozamites Leckenbyi. 



9. Nilsonia compta. 



10. Podozamites lanceolatus. 



IL Ctenis sulcicaulis. 



12. Ginkgo digitata. 



1-3. Taxites zamioides. 



14. Brachyphyllum mamillare. 



Fourteen out of the 37 well-characterized species not new. 

 In common with the Siberian Jurassic there are the following 



Cladophlebis acutiloba. 

 Thyrsopteris Murrayana. 

 Nilsonia orientalis. 

 Nilsonia parvula. 

 PterophyUum rajmahalense. 

 Podozamites pulchellus. 

 Podozamites lanceolatus. 

 Podozamites lanceolatus minor. 



9. Podozamites lanceolatus latifolius. 



10. Ginkgo digitata. 



1 1 . Ginkgo Huttoni. 



12. Ginkgo lepida. 

 1.3. Ginkgo sibirica. 



14. Seeds of Ginkgo. 



15. Pinus Nordenskioldi. 



16. Brachyphyllum mamillare. 



Sixteen out of the 37 determined species not new. 



The Oregon strata rival those of eastern Siberia in the development 

 of Ginkgos, and it is a noteworthy fact that nearly all the more impor- 

 tant species made by Heer from those beds have similar forms in the 

 Oregon strata. This similar great expansion of Ginkgos is strong proof 



