F. II. Knowlton — Jurassic Flora of Oregon. 4T 



Cycadites. Danceopsis Storrsii shows affinity with D. maran- 

 tacea Heer, and D. Rumpfii Schimper, two Triassic species, 

 though it is smaller. Ctenophyllum angusti folium, as Fontaine 

 points out, is "plainly one of the narrow-leaved Ctenophylla 

 of the type of Ctenophylhcm Braunianum (Gopp.) Schimper." 

 Podozaviites pachyphyllum resembles a number of species, 

 but is especially like Pterophyllumf cteniforme Nathorst, 

 from the Rhaetic of Sweden. Williamsonia oregonensis very 

 much resembles W. gigas (Will.) Carruthers, a well-known 

 species of the Jurassic of France and elsewhere. Tmniopteris 

 orovillensis, the most common fossil plant at Oroville, is very 

 near the plant figured and described by Saporta as T. tenuiner- 

 vis Braunn from the Infralias of France. Macroiijeniopteris 

 californica, which is also a common form at Oroville, is near 

 T. lata Oldh. & Morr., of the Rajmabal flora of India. Angio- 

 pteynditim californicum is quite similar to A. McClellandi 

 (Oldh. & Morr.) Schimper, from the same locality and hori- 

 zon as the last. 



This comparison could be much further elaborated, but it is 

 perhaps unnecessary. 



A Comparison or the Jurassic Floras of California and 

 Oregon Here Considered avith Knoavn Jurassic Floras 

 OF Other Parts of the World. 



The Jurassic flora is one of the most widely known and uni- 

 formly distributed of any known fossil flora. Reaching its 

 northernmost limit on King Karl's Land, 82° N., and its south- 

 ernmost extension on Louis Philippe Land, 63° S., it is found 

 entirely round the world in almost every continent and coun- 

 try — North America, Europe, Asia, Australia. Throughout 

 this vast area it is to all intents and purposes practically the 

 same flora. For example, many of the forms discovered on 

 Louis Philippe Land are identical, or closely related, to those 

 of the Oolite of Yorkshire, England, while many forms, identi- 

 cal or closely related, are common between the areas in Eng- 

 land, Sweden, France, Italy, Germany, Siberia, China, Japan, 

 India, or ISTorth America. 



The types of the Jurassic flora are for the most part well 

 marked, and even when only fairly well preserved are capable 

 of very certain identification. When to this is added the fact 

 that in most areas where this flora has been found its position 

 is confirmed by contributary stratigraphic and paleontologic 

 data, the fixation of a similar flora found in a new area is made 

 easy and certain. 



It is proposed to compare the flora here under consideration 

 with that of several of the more important of the known 

 Jurassic floras of the world, beginning with that of Eastern 



