50 F. H. Knowlton — Jurassic Flora of Oregon. 



considerable element of the Oroville flora occurs in xilaska in 

 association with an invertebrate fauna acknowledged to be of 

 Middle Jurassic age, it would seem to follow that the Mariposa 

 is also of similar age. The interpretation of the bearing of the 

 invertebrates on this question must naturally be left to the 

 invertebrate paleontologists, but this much can be said : The 

 plant evidence, as above stated, is distinctly in favor of regard- 

 ing the Mariposa as much older than "late Jurassic." 



Other localities in Alaska are as follows: From Herendeen 

 Bay, in association with shells of Aucella crassicollis, we have 

 Pterophyllutn alaslcense Font., a form very closely related to 

 P. rajinahalense, in fact hardly to be separated from it. The 

 latter species is one of the most abundant and important of 

 those found in the Oregon locality, l^ear Nikolai in* the 

 Copper River region occurs Sagenopteris alaslcense Font., 

 which is near S. Goppertiana of the lower Oolite of Italy, and 

 which is found also at Thompson Creek, Elk River and Oro- 

 ville. From the vicinity of Cape Lisburne quite large collec- 

 tions have been obtained. These comprise 14 species which 

 were considered by Fontaine to be of jurasso -Cretaceous age, 

 but a study of large additional collections since secured, 

 together with a review of much of the original material, has 

 convinced the writer that they are of the same age as the other 

 Alaskan and Pacific Coast plant beds. About half of the 

 Cape Lisburne species are identical with those of Oregon or 

 California. The final locality is between Icy Cape and Wain- 

 wright Inlet, some 180 miles northeast of Cape Lisburne. 

 This place has afforded Podozamites sp. and Baiera graeilis, 

 the latter a species characteristic of the Yorkshire beds. 



On account of the larger number of common species, the 

 next area to be compared, although not logically next from a 

 geographical point of view, is Yorkshire, England, which has 

 in common with the California-Oregon region the following : 



Marchantites erectus Plerophyllum minus 



Cladophlebis denticidata Nilsonia compta 



Cladophlehis haiburnensis Podozamites lanceolatus 

 Coniopteris hymenophylloides ? Ctenis sulcieaulis 



Thyrsopteris Murray ana Cycadeospermum Buchlandiif 



JRiiffordia Gopperti Ginkgo digitata 



Tceniopteris major Taxites zamioides 



Tceniopteris vittata ' JBrachyphyllum mamillare 



Sagenopteris paucifolia Pagiophyllum Williamsonis. 

 Ptilozamites Leckenbyi 



The flora of the Yorkshire beds has been made the subject 

 of an exhaustive study by Seward,* published in 1900. The 

 *Cat. Mesoz. PI. Brit. Mus., Jurassic FL, I., Yorkshire Coast. 



