Permo-Carboniferous Ammonoids of the Glass Mountains 3 



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still very doubtful if any of our species belonging to Marathonites 

 have anything to do with Stacheoccras Konianozuskyi and St. Ganti. 

 Of the first of these species we do not know the internal suture and in 

 the second the internal lobes seem to be entirely different from those 

 of Marathonites. On the other hand, Agatliiceras FrecJii is not of 

 great importance, because the species of this genus change very little 

 from the Carboniferous up to the Permian. 



More interesting is the occurrence of Daraelites as this genus so far 

 has only been found in the Permo-Carboniferous; but the species is 

 very different from those described from the Artinsk and the Sosio 

 beds. 



Most interesting is also the genus Uddenites. There is no doubt 

 that it represents a branch of Pronorites, as the inner whorls show 

 the typical Pronorites suture. Pronorites is known to exist in the up- 

 per Carboniferous as well as in the Permo-Carboniferous, but it seems 

 that not before this latter period does it begin to split up into different 

 branches. Uddenites apparently represents the oldest of these 

 branches which developed from the type genus as a side branch be- 

 cause the type continued to exist until the Artinsk stage. No branch 

 of the Pronorites tribe seems to have developed during the upper 

 Carboniferous. 



Only two forms in our list are strongly related to upper Carboni- 

 ferous forms; namely, Gastrioceras modcstum and Schistoceras diver- 

 secostatum, but their relatives also have only been found in the very 

 highest part of the Pennsylvanian. 



The absence of all more highly developed ammonoids, especially 

 Medlicottia, the presence of types that are nearly related to such as 

 have been found only in the highest Pennsylvanian and others that 

 are exclusively from the Permo-Carboniferous, the occurrence of gen- 

 era that are different from anything so far discovered in the Carbon- 

 iferous and the Permo-Carboniferous, makes our fauna a unique one 

 and shows at the same time that it represents one older than the oldest 

 Permo-Carboniferous so far known, but younger than the highest 

 Carboniferous. Our fauna would thus range between the Uralian and 

 the Artinsk; or, as we take this latter expression as the name of a 

 stage, .we might say that our fauna belongs to the Artinsk but is 

 older than the cephalopod-bearing sandstones of this stage. This also 



