Fermo-Carboniferous Ammonoids of the Glass Mountains 43 



lower, the Virgal groups the middle, and the Chideru group the upper 

 Productus limestone. In another paper, Noetling^ says he considers 

 that the Sicilian Fusulina limestones (Sosio beds) are older than 

 the Russian Artinsk and this older than the Productus limestone. 

 Thus neither the Artinsk nor the Sosio beds would be represented in 

 the Salt Range. 



An entirely different opinion is held by Tschernyschew. He thinks 

 that the Talchir, Dandote and Warcha groups represent the middle 

 Carboniferous, that the lower and middle Productus limestones are 

 equivalent to the upper Carboniferous, and that only the highest part 

 of the middle and the lower part of the upper Productus limestone 

 are of Permo-Carboniferous age, while the rest of the upper Productus 

 limestone would correspond to the lowest part of the Russian Permian. 

 Tschernyschew based his views principally on the character of the 

 brachiopods contained in the Salt Range deposits, which he compared 

 with those of the Russian Carboniferous. 



Tschernyschew's views have not been accepted -by most of the 

 authors who had an opportunity to compare the Indian faunas with 

 those of other parts of the world; neither Noetling, nor Freeh, nor 

 Diener, nor Haug, are' inclined to adopt the opinion of the Russian 

 scholar. Haug (Traite de geologic, p. 808) says that if the base of 

 the deposits is Uralian, the Artinskien is probably represented by 

 the lower par-t of the middle Productus limestone, while the upper 

 part of the middle Productus limestone would be equivalent to the 

 Saxonian and the upper Productus liniestone correspond to the 

 Thuringien, , -:<; 



Most of the modern authors base their classification of the Salt 

 Range on the cephalopods contained in them. Unfortunately am- 

 monoids have been found only from the upper part of the Middle Pro- 

 ductus limestone (Kalabagh beds) upwards, but practically all the 

 modern authors concede that the ammonoids contained in those beds 

 are of a very highly developed Permian type. 



The upper part of the middle Productus limestone carries the genus 

 Xenaspis, which has its nearest relatives in the Triassic; and Xenodis- 

 cns, which occurs much more frequently in the Triassic than in the Per- 

 mian. Its ancestors in the Permo-Carboniferous are not well known. 



'Noetling, Medlicottia u. Episageceras, p. 354. 



