(U F. II. KnowUon — Jurassic Flora of Oregon. 



0. The Jig-e of tlie beds containing the "Jurassic flora of 

 Oregon" thus hinges on the rehitive strength of the evidence 

 afforded by the flora as compared witli tliat of the associated 

 fauna. It has been shown in this paper that of a total of 100 

 species of plants, 47 species are known also fi'om known J urassic 

 of other, often widely separated, parts of the world. Only one 

 of these 100 species has been found in the Lower Cretaceous 

 beds of the region. The total Knoxville fauna comprises 77 

 forms of invertebrates, only 7 named species of wliich have 

 been found associated with the Jurassic plants. Of these 7 

 species of invertebrates, only a single species has been found 

 outside the limits of the Oregon-California area, and it has 

 been further shown that the invertebrate paleontologists are 

 not in accord among themselves as to the interpretation t© be 

 given tlie age determination of the fauna. The conclusion is 

 reached that the plants, being thoroughly consistent, afford 

 the better criteria, and the beds are regarded as unquestion- 

 ably of Jurassic age. 



7. From the paleobotanical evidence which has been pre- 

 sented it follows that in this portion of the Pacific Coast region 

 the line between the Jurassic and Cretaceous is to be drawn 

 througli the upper part of the Knoxville formation, and not at 

 its base. This line is fixed by the upper limit of the Jurassic 

 flora. 



