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PROCEEDINGS OE THE GEOLOGICAL SOCIETY. 



[Mar. 6, 



to people the sea-bottom of the South Yorkshire region during the 

 aggregation of the beds. 



B. Fossils of the Broiherton Beds. — Little can be said relative to 

 any peculiarities in the distribution of fossils in the Brotherton Beds. 

 The chief feature is most certainly their great paucity both specifi- 

 cally and individually. The three species which occur in them are 

 generally associated ; when any one of them is found alone, it is 

 Accinus dubius. Their occurrence is not general throughout the 

 vertical thickness of the beds, there being many of the strata quite 

 unfossiliferous. They characterize certain strata, and on the upper 

 surfaces of these they are often rather thickly strewed. The 

 size of the two Conchifers which occur is greatly reduced in the 

 Brotherton Beds, more particularly in the case of Ax. dubius. Here 

 it never exceeds half-an-inch in width, while in the Lower Lime- 

 stone it is at times fully two inches. It also shows slight modifica- 

 tions of form, approaching in outline the variety Schlotheimi of 

 Geinitz, though somewhat intermediate between it and obscurus. 

 The only species peculiar to these beds is the Alga already noticed. 



§ VI. Permian Fossils of South Yorkshire compared with those 

 of Durham. — An examination of the preceding table shows that all 

 the species, with the exception of two, occur in the Permian beds of 

 Durham ; and both of these are found in the Lancashire beds. It is 

 thus seen that none are peculiar to South Yorkshire. It is also 

 evident that most of the species are not confined to the British area, 

 several being among the most sporadic of Permian species. Out of 

 the 31 species 25 are common to Germany and Britain, most of 

 which existed in the former region at the period of the Lower Lime- 

 stone. Ten species are common to Russia and Germany, and a less 

 number (4) to Russia, Germany, and the Permian strata of North 

 America. The Conehifera, along with the Cephalopod and the Bra- 

 chiopod, are all extra- British ; two-thirds of the former and each 

 of the representatives of the latter classes range through Germany 

 into Russia. All the Polyzoa are German ; but none are Russian. 

 The Entomostraca, with one exception (Bairdia Schaurothiana), are 

 German, one (Kirhbya Permiana) having also Russian varieties. 

 The Rhizopod is a Zechstcin species. The species most confined in 

 their range are Gasteropods. Of the members of this class only one 

 is Bussian, 5 are German, and 3 are peculiar to Britain. In all, 

 5 species appear to be confined to the British area. 



Compared with the Permian fauna of Durham — taking it at its 

 maximum development during the deposition of the Shell-limestone 

 — the groiip of species found in the Lower Limestone forms but a 

 meagre life-group so far as number of species is concerned. The 

 number of species composing the former is 118, while of the latter 

 there are only 31. This does not, however, prove a rarity of life in 

 the Yorkshire area ; for the fewness of species seems to have been 

 counterbalanced in some degree by a greater individual abundance, 

 — the remains of GervUUce at Wentbridge, ifec, and of Turbo helicinus 

 at Hampole, exceeding an)i;hing of the kind to be observed in the 

 most fossiliferous localities of Durham. The chief differences are 



