Vol. 68.] SUCCESSION IT^ THE NORTH-WEST OF ENGLAND. 



471 



limestone, passing in places into more shaly and platy beds. The 

 beds mark the beginning of the depression which reached its 

 maximum in the overlying Lower DihunopJiyllum Sub-zone. Except 

 in the Kendal District, this horizon is usually notable for a con- 

 siderable development of secondary silica, and the fossils are often 

 preserved in beekitei 



The fauna is characterized chiefly by the abundance of the 

 index-fossil, together with Seminula and small gastropods, and by 

 the absence of Orthotetinse and CJionetes, while Productus corrugato- 

 Jiemisj^hericus and Litliostr otion martini are still abundant. Pugnaa? 

 jiugnus is first met with in this sub-zone, but is very rare. 



Fauna. 



Cyatliocrinus sp. 



ArchcBOcidaris plates. 



Aulopora sp. 



Lithostrotion martini Ed. & H. 



Syringopora geniculata Phill. 



Spirorhis sp. 



Atliyris j^lctnosulcata f Phill.). 

 Cyrtina carbonaria (M'Coy). 

 Prochcctus comigato-heiH ispliericns 



Vaughan. 

 Fo'oductus elegans M'Coy. 

 Froductus laciniatiis Sby. 

 Vroductus punctoMs Mart, 

 Pugnax picgnus (Mart.). 

 Ehynchonella sp. 



Ehixndomella michclini (L'Eveille). 

 Semimda ficoidea Vaughan. 

 Spiriferina laminosa (M'Coy). 

 Spirifer hisulcatus Sby. 



Bellerophoii costatus Phill. 



Bellerophon obsoletus M'Coy. 



Flemingia sp. 



Loxonema rugiferum Phill. 



Murcliisonia sp. 



Pleurotomarla (Ptychomphalus) 



vittata Phill. 

 Pleurotomaria sp. 

 EMneoderma fragile de Eon. 

 Schizostoma catillus (Mart.). 

 Straparolhis sp. 

 Turhonitella biseriaUs (Phill.). 



Psephodus magnus M'Coy. 



Geographical distribution. — Typically developed along the 

 base of the Shap-E-avenstonedale escarpment between Long Scar 

 Pike and the Dent Fault, but dies away into the upper portion 

 of the Orton Sandstone before reaching Shap village. In the old 

 Kettlewell quarries and on Cunswick Scar in the Kendal District, 

 In the Arnside and Grange Districts it cannot be distinguished as a 

 separate horizon. In the Pennine Escarpment it appears to be 

 represented by the unfossiliferous sandstone underlying the Mel- 

 merby Scar Limestone, in Swindale Beck and High Cup Gill. 



{g) The Nematophijllum-minus Sub-zone. 



This sub-zone forms one of the most important horizons, on 

 account of its presence in all the districts throughout the North- 

 Western Province. It is, however, much better developed in some 

 districts than in others. In the type districts and on Kendal Eell 

 it rests on the Cyrtina-carhonaria Sub-zone, but, where that 

 horizon is absent in the "Western Districts, the lower limit is taken 

 at the base of the compact white limestone which rests upon 

 the darker, more bituminous gastropod-beds of Eed Hills under 



