142 MESOZOIC FLORAS OF UNITED STATES. 



The following species and varieties have been found in the Oregon 

 and Oroville strata and elsewhere in Jurassic beds: Sagenopteris Gcepper- 

 tiana, Pterophyllum rajmahalense, Podozamites lanceolatus, Podozaniites 

 lanceolatus latifolius, Pinus Nordenskioldi, 5 in all. 



We find, then, that the Oroville and Oregon beds have in common 

 12 out of 37 fairly well-characterized species, nearly one-third. This 

 shows pretty conclusively that whatever the age of these strata may be 

 it is essentially the same. But these last-named 5 species are found in 

 other localities besides the Oroville and Buck Mountain regions. 



Sagenopteris Gceppertiana, according to Zigno, occurs in the Lower 

 Oolite of Italy. Pterophyllum rajmahalense was first found in the 

 Rajmahal series of India, which is held to be Liassic in age; but it does 

 not differ apparently from Heer's Pterophyllum Sensinovianum, so, if 

 Heer's conclusions as to the age of the strata containing it are correct, 

 we may assume that it persists into the Lower Oolite. Podozamites 

 lanceolatus genuinus, or Podozamites lanceolatus simply, is, like Clado- 

 phlebis whitbiensis, probably a much abused type of leaf. It probably 

 is not a species, but rather a type of leaf found in many species which 

 lived in Jurassic times. The original is from the Lower Oolite and the 

 form is probably more characteristic of that period than any other of the 

 Jurassic. The broad form, var. latifolius, seems to be more common in 

 the Oohte than in any other epoch. Pinus Nordenskioldi is apparently 

 also especially characteristic of the Lower Oolite. This, too, is probably 

 not a single species, but rather a type of Pinus leaf that was common in 

 the Lower Oohte. It is quite probable that some of the forms placed in 

 this species are really Taxites. 



There remain 25 species that, as yet, have not been found at the 

 Oroville locality. These, taken in connection with some of the last 

 mentioned as common to Oregon and Oroville, show a remarkably large 

 proportion of plants common to the Oregon beds and the two widely 

 separated regions, Yorkshire in England and eastern Siberia. The 

 element common to Oregon and eastern Siberia might be explained by 

 supposing that in Jurassic times land' connection existed between Asia 

 and northwestern America. It is difficult to understand why so many 

 forms should be common to England and northwestern America. In 

 this connection it is interesting to note that several of the forms made 



