498 



PROF, T. R. JONES AND MR. J. W. XIRKBT ON OSTRACODA OF 



favoured by him with the following synopsis of the Carboniferous 

 strata of Northumberland * : — 



Series 



Carboxiferous Limestone Series. 



Northumbrian Type. 



( Felltop Division : between the Millstone G-rit and the zone 

 of the Great Limestone : Sandstones and Shales ; one 

 or more beds of Marine Limestone ; some Coals. 

 Upper Limestone j (450 to 1200 feet.) 



Sot.i'Qo '^ Calcareous Division : from the Great Limestone down to 



the bottom of the Dun Limestone or Eedesdale Lime- 

 stone. Many beds of Marine Limestone : Sandstones 

 l^ and Shales; some Coals. (1300 to 2500 feet.) 



( Carbonaceous Division : the Scremerston beds of North 

 Northumberland ; beds prevalently Carbonaceous ; 

 Limestones, chieily thin, many of them containing 

 vegetable matter ; Coals. (800 to 2500 feet.) 

 Tuedian Division. 



Upper Tuedian or Fell Sandstone Group. Great zone 

 of massive grits (Larriston Fells, Bewcastle Fells, 

 Peel Fell, Simonside and Harbottle Hills, Chilling- 

 ham, &c.). Shales partly greenish and reddish ; 

 Coals few, tliin, and in many districts absent. (600 

 to 1500 feet.) 

 Lower Tuedian or Cement-limestone Group : cement- 

 stones passing (at Eothbury and Bewcastle) into 

 Limestones ; Coals very rare ; many of the Shales 

 \^ and Sandstones coloured. (500 to 2000 feet.) 



Basement Conglomerates (Upper Old Eed Sandstone) ; local. 



Lower Limestone 

 Series 



Carboniferous Limestone Series. 

 Scotland — Northumberland — Yorkshire. 



Scottish Type. 



Northumbrian. 



j'' Upper Limestone 

 Group. 

 Middle or Coal and 



Carboniferous 



Limestone , ironstone Group 



^^^^^^i I Lower Limestone 



(^ Group. 



Calciferous 

 Sandstone 

 Series 



Upper or Cement- 

 stone Group. 

 ' Lower or Eed Sand- 

 stone Group. 



I 



; 



Yorkshire. 



Upper part of the 

 Upper Lime- 

 stone Series. 



Lower part of the 

 Upper Lime- 

 stone Series, to- 

 gether with the 

 Lower Carb. L. 

 Series, including 

 Basement-beds. 



Carboniferous 

 LimestoneSeries, 

 including the 

 beds between the 

 Little Limestone 

 and the Mill- 

 stone Grit, the 

 Yoredale Beds, 

 and the Lower 

 Limestone-shale. 



We cannot go further into this matter just now, and we have, 

 perhaps, said enough to show that, in using the term Yoredale for 

 the whole of the North of England in the following remarks and 

 Tables, we do so in a somewhat conventional sense, so far as it 

 relates to Northumberland. It may be added that Ostracoda are so 

 plentiful in these strata, and occur on so many horizons, that the 



* Encycl. Britann. 9th edit. vol. xvii, p. 574. 



