Vol. 68.] SUCCESSION IX THE NORTH-AVEST OF EXGLAXD. 491 



Pebble-Bed, occurs a short distance below the farm. Above Waters 

 Farm a bed of hard calcareous mudstoiie^" crops out on the left 

 bank of the stream, and from it the following species have beeiL 

 collected : — 



Syringojwra cf. distans FiscLer. I Seminula amhigua (Sby.). 



Lithostrotioii martini M. Edw. S-pirifer sp. 



Allorisma variabilis (M'Coy). 

 Aviculopecten cf. intcrstiiialis Hind. 

 Crcnipccien semicircidaris (M'Coy). 



Zaphrcniis cnnisJcilleni M. Edw. 



Profhictus cf. jmnctatus Mart. 

 Producius cL pyxidiformis de Kon. 

 Rhipidomella michelini (L'Eveille). 



This fauna is evidently the attenuated representative of that 

 which characterizes the lower portion of the Gastropod Beds at 

 Blackstone Point in the Arnside District, described later, and 

 shows that this sub-zone (as well as the greater portion of the- 

 JlicJielinia Zone) is merged in the Orton Sandstone. South of 

 Docker Beck very few exposures are met with in the sandstone, 

 jind these contain only casts of Stigmaria. South of Long-Scar 

 Pike, however, a calcareous mudstone occurs, resembling that just 

 described above "Water's Farm. As we pass to the south-east of 

 Ihe Shap District, the sandstone episode begins at progressively 

 higher horizons; so that the lower portion of the Gastropod 

 Beds as well as the Miclielinia Zone eventually crop out as cal- 

 careous deposits beneath the sandstone on Piavenstonedale Moor, 

 and in the neighbourhood of Scandal Beck. Above the sandstone 

 the lowest layers of the limestone which underlies the Cgriina- 

 carbonaria Sub-zone on Orton Knott, appear also to belong to this- 

 stib-zone ; they include bands of lighter-coloured breccia, embedded 

 in a darker, more ciystalliue, matrix. It seems jDrobable that, in. 

 this case, the breccia is due to contemporaneous erosion. 



The Cyrtina-carhonaria Sub-zone has not been observed in 

 the Docker-Beck section. It appears to be merged in the upper 

 portion of the Orton Sandstone. A short distance to the south, 

 however, it is met with below Long-Scar Pike, and it gradually 

 increases in importance as it is traced eastwards into Bavenstone- 

 dale. The lithological characters and organic contents of this 

 sub-zone have already been described (see pp. 470-71). 



Localities. — Long-Scar Pike, Orton Knott, Sunbiggin, Severals, 

 and Smardale Gill. 



The NematojjJiyUum-minus Sub-zone is comparatively thin 

 in the neighbourhood of Shap ; it is exposed near a dried-up pond, 

 about 80 yards west of ' The Nab ' Farmliouse, and also near the 

 head of Docker Beck. It is neither so thick nor so well developed 

 as in the Western Districts, and Clionetes 2)(ipii^onacea is a rare 

 fossil here, although so abundant at this horizon in the Arnside 

 and Grange Districts. The rock is a grey limestone, weathering 

 white. The sub-zone increases in thickness as it is traced s6uth- 

 wards and eastwards into the Bavenstouedale District. The 

 index-fossil occurs somewhat abundantly, and is accompanied by 



