ANTHRACOLITHIC ROCKS OF KANSAS 157 



The question about the Artinsk can be solved by comparing its fauna with the 

 fauna of the Permian lying higher and that of the upper Carboniferous lying 

 lower. I think there would be more resemblance with the fauna of the upper 

 Carboniferous. However, the thickness of the Artinsk and the Permian is not 

 very great and their fauna may not be very different. On the other hand some 

 Russian authors are inclined to relate Artinsk to the Permian system; they do so 

 on historical foundation, as the extent of the Carboniferous system had been 

 determined in science before Murchison and we have no right to enlarge it by 

 adding Artinsk. We may sooner unite Artinsk with the Permian system, the 

 extent of which is not so definitely established as that of the Carboniferous. In 

 Russia the term Permocarboniferous is used to designate Artinsk, if it is not 

 related to the Permian nor to the Carboniferous systems, but placed between 

 them, as done by Karpinsky (though without sufficient paleontological grounds), 

 when he established Artinsk. If Artinsk is united with Carboniferous system, 

 the term Permocarboniferous will not have to be used in the sense just mentioned, 

 it will be superfluous. No one in Russia is inclined to designate by the name 

 Permocarboniferous the total of the Permian and the Carboniferous systems, 

 as it is sometimes done in the West of Europe. The Russians keep to one of the 

 two opinions, they either take Artinsk for the Permocarboniferous, that is for 

 the intermediate between the Carboniferous and the Permian, or unite it with 

 the Permian. But I do not think anyone would unite it with the Carboniferous. 

 I think that there might be Artinsk in Kansas and in Nebraska, as there is much 

 in common between the Donetz fauna described by me, with the fauna of Kansas 

 and Nebraska. But whether the Permian fauna exists in North America is an 



open question to me 



Yours sincerely, 



Nicholas Yakowlew 



Dr. Fritz Freeh, the distinguished professor of geology in the 

 University of Breslau, has w^ritten me as follows under date of Decem- 

 ber 21, 1909: 



Answering your kind letter of the end of October I give my opinion on the 

 Dyas [Permian] as follows: I include the Arta [Artinsk] stage in the lower Dyas 

 as the type of this lower stage. I have had no ground to change the opinions, 

 expressed in Lethaea palaeozoica (2. Band, commencing on p. 493), concerning 

 the correlation of the Dyas. 



A letter from Alexander Krasnopolsky, Geologue en chef du 

 Comite geologique de Russie, was received January 6, 1910, a trans- 

 lation of which follows: 



The Permo-Carboniferous deposits of the western slope of the Urals — 

 investigated by me — represent two formations, the Artinsk and the Kungur. 



