Prof. C. Lapworth — Cambrian Rocks at Nuneaton. 321 



B. Hartshill Quartzite. — Thick-bedded quartzite, with intercalations 

 of sandy shales. This formation extends from Tuttle Hill to Harts- 

 hill, and is exposed in many large quarries. The basement beds of 

 the quartzite contain abundant fragments of the Caldecote volcanic 

 rocks. At Mr. Boon's quarry, between Caldecote Lodge and Tuttle 

 Hill, its lowest zone is laid bare, and is almost wholly made up of 

 this derived volcanic material. 



Along a straight line ranging from the Midland Bailway Station 

 at Nuneaton to the village of Hartshill, near Atherstone, the highest 

 zone of the quartzite is succeeded by the 



C. Stockingford Shales. — A thick group of purple, green, grey and 

 black thin-bedded shales, which are separable into two main 

 divisions : — 



(1) Purple and Green Shales (Obolella Beds). 



The lowest zones of this division are stained of a deep purple 

 colour, and were formerly worked for manganese. Higher up the 

 purple shales pass up into green and grey beds, but the red beds 

 re-appear at intervals to the summit of the division. At Marston 

 Jabet, Camp Hill, and in many localities beyond Hartshill, fossils 

 occur, which are, however, limited to very thin seams. The com- 

 monest forms may be provisionally referred to: — 



Lingulella pygmea, Salter. Protospongia fenestrata, Hicks. 



Obolella sagittalis, Salter. Acrotreta socialis, Von Seebach. 



Orthis lentimlaris , Dalm. Obolella Salteri, Holl. 



(2) Gray shales with bands of intensely black carbonaceous shales 

 (Agnostus Beds). 



These are divisible into two main zones : — 



(a) Zone of Agnostus sociale, Tullberg. 



The characteristic fossil of this band is the well-marked variety 

 of Agnostus pisiformis (Linn.), which gives its name to the zone. 

 It has been met with in these beds at Chilvers Coton, Stockingford 

 Cutting, and Oldbury Beservoir. 



Another very characteristic fossil in the band is Beyrichia Angelini, 

 Barr., a well-known Swedish species. Its associated forms are a 

 species of Lingulella, apparently identical with Lingulella Nicholsoni, 

 Callaway, and a species of Obolella. 



(b) Zone of Sphcerophthalmus alatus, Beck. (? = Zone of Peltura 

 scarabeoides, Wahlenberg). 



The characteristic fossil of this zone is the well-known Scandi- 

 navian species S. alatus (S. humilis, Phill.), already known from 

 the British Upper Cambrian rocks of North Wales and the Malvern 

 Hills. 



It is associated with abundant specimens of an Obolella of the type 

 Obolella sagittalis, Salt., but with strongly-marked concentric lines 

 of growth (var. concentricus). Species of Agnostidce occur more 

 rarely, together with carbonaceous remains resembling the Mymeno- 

 caris vermicauda of Salter, etc. 



The examples of Sphcerophthalmus are locally abundant but poorly 

 preserved, head, body-rings, and free cheeks. They are confined, 



DECADE HI. VOL. III. — NO. VII. 21 



