F. H. KnowUon — Jurassic Flora of Oregon. 57 



fauna, such as Belemnites tehammnsis, Hoplites Storrsii, and 

 some of the Tiirbinidse, that resemble European Upper Jurassic 

 types. Aucella Piochii belongs to the same general type as 

 A. mosquensis, which has usually been referred to the Jurassic, 

 and it is somewhat closely related to the Aucellse of the Mari- 

 posa beds ; but Professor Pavlow informs me that Aucellse 

 very similar to A. mosquensis occur in the Neocomian of 



Russia also. These resemblances are not considered 



of sufficient importance to counterbalance the evidence of the 

 Cretaceous age of the entire series. Some Jurassic elements 

 are naturally to be expected in the Lower Neocomian, and it 

 is well known that in Eui'ope several species of ammonites 

 pass up from the Jurassic to the lowest Cretaceous beds." 



On the other hand, Prof. A. P. Pavlow,* the distinguished 

 Russian geologist and paleontologist, in reviewing the Knox- 

 ville species of Aucella, takes issue with Doctor Stanton as to 

 the age of the beds. He says : "I share perfectly the opinion 

 of Diller and Stanton that the different parts of the Knoxville 

 series contains each its own Aucella fauna, which becomes modi- 

 fied gradually. But I cannot share the opinion that all the 

 Knoxville ought to be referred to the Cretaceous system. At 

 least in that which concerns its lower part characterized by 

 Aucella Gdbbi {Aucella Piochii type) I do not find data suffi- 

 cient to take this side, since the Aucella beds speak more in 

 favor of placing these lower beds in the Portlandian, or per- 

 haps in the Aquilonian (though for this last there are only a 

 few indications). The upper part of the series, which is the 

 larger (2000 feet), offers an Aucella fauna of the character of 

 the Lower Cretaceous." 



If tbis view be accepted — and it may be added that it corre- 

 sponds well with the plant evidence — the Knoxville will be 

 divided into two parts, of which only the upper (2000'±) will 

 be Cretaceous, while the remainder (18,000') of the great sec- 

 tion will be relegated to the Jurassic. Professor Pavlow was 

 of course unaware of the fact that the two species of Aucella 

 {A. Piochii and A. crassicoUis) overlap in range to the extent 

 just shown at Elk River and elsewhere, and the deciding factor 

 in drawing the Jurasso-Cretaceous line may well he the 

 floras. 



Another one to write upon the subject is Dr. Emil Haugf 

 of Paris, who, after enumerating a number of Knoxville forms, 

 which he says "have for a long time been parallelized with the 

 Neocomian of Europe," proceeds as follows : "However, the 

 work of Mr. Stanton contains also several Hoplites, described 

 as new species, but which are close neighbors of species of the 



* Nuov. M^m. Soc. Imper. Nat. Moscow, vol. xvii, p. 83, 1907. 

 ^ Bull. Geol. Soc. France (3), vol. xxvi, p. 326, 1898. 



