62 Br. Wheelton Hind — Carboniferous Life-Zones. 



(with subdivisions and some small local variations), whicli are as 



follows : — 



Upper Zone : 



Spirifer fasiger, Productiis corn, Spirifer supramosque'nsis, 

 Conocardium TJralicum, Schioagerina princeps, Margini- 

 fera Uralica, with coal in the Donetz. 



Middle Zone : 



Spirifer Mosquensis. 

 Lower Zone : 



Productus giganfeiis, P. striatns, CTionetes papilionacea, with 

 coal-beds in Central Kussia. 



It is to be noted that in the Donetz basin the biological division 

 between the upper and lower divisions is not absolute, Spirifer 

 Mosquensis passing well up into the beds with Productus cora ; but 

 it would appear that Spirifer fasiger, Keys, does not ti'espass into 

 the zone of S. Mosquensis, and the two fossils are never found 

 together. 



A large number of widely distributed Carboniferous species are 

 common to all three divisions, but are not so frequent in the upper; 

 and this, in addition, contains several forms which have never been 

 noted in Western Europe, but which, on the other hand, are 

 recognized as occurring in beds of the Salt Range period of India, 

 and in the Carboniferous beds of North America. 



Passing to the Carboniferous beds of Western Europe, De Koninck 

 and Dapont are able to recognize three subdivisions in the calcareous 

 deposits of Belgium : — 



Stage III. — Upper — 



Yisean (detrital) : Zone of Productus giganteus, P. latissimus, 

 P. striatus, P. cora, Chonetes papilionacea. 



Stage II. — Middle — 



WAULSORTiAN(corallian): Amplexiis coralloides,SyringotTiyris 

 cuspidatus, Spirifer striatus, Conocardium Hibernicum. 



Stage I. — Lower — 



TouRNAisiAN (crinoidal) : Spirifer Tornacensis, S. cinctus, 

 S. laminosus, Syringothyris distans, Athyris Boyssii, 

 A. lamellosa, Conocardium fusiforme, etc. 



This threefold division, however, is not accepted by all Belgian 

 geologists. The Legende de la Carte geologique de la Belgique, 

 dated 1896, shows only two main zones in the Carboniferous Lime- 

 stone of Belgium — Visean and Tournaisian — the assise de Dinant, 

 with Chonetes papilionacea, being considered as a facies of the 

 Yisean. The Waulsortian beds are placed as a facies of the Tour- 

 naisian, not typified, however, by any fossils ; and the assise of 

 Hastiere, with Spirifer Tornacensis, S. glaher, and Spiriferina octo- 

 plicala, is considered to belong also to the lower group. 



