656 DR. G. J. HINDE AND ME. HOWARD FOX ON [Nov. 1 895, 



IX. Position of the Badiolarian (Codden Hill) Beds in 

 the Lower Culm Series. 



It has been already mentioned that De la Beche states very 

 distinctly that in North Devon there is no evidence of uncon- 

 formity between the Devonian and Carboniferous or Culm Measures, 

 but that there is a gradual passage from the shales and slates of 

 the Upper Devonian rocks into black carbonaceous shales and lime- 

 stones with an abundance of Posidonomyce. These black beds 

 have been generally regarded as the lowest fossiliferous beds of 

 the Culm Measures, both in North and South Devon and in 

 Cornwall. They contain but few species of fossils ; as shown in 

 the List given above, there appear at present to be but 7 species 

 known in them, namely 3 species of Posidonomya, including 

 P. Becheri, Goniatites sphcericus, Mart., G. crenistria, Phill., G. stria- 

 tus, Sow., and Orthoceras cylindraceum, and none of these forms has 

 as yet been met with in the Badiolarian (Codden Hill) Beds. 

 These dark Posidonomya-lim.estoia.es and shales are shown more 

 particularly near Fremington, and at Venn and Swimbridge, near 

 Barnstaple, also at Bampton in North Devon and near Wooladon, 

 Lifton, etc., in the Launceston district. "We think that there is 

 sufficient evidence for the view that these rocks occupy a lower 

 position in the series than the Radiolarian (Codden Hill) Beds. As 

 already mentioned, we have ourselves observed in the Wooladon 

 quarries near Launceston a clear upward succession from the dark 

 limestones and shales containing Posidonomya into cherty rocks 

 containing radiolaria, which appear to be the lower beds of the 

 Badiolarian Series. Mr. Ussher, on the other hand, 1 gives no 

 decided opinion as to the order of succession in the Lower or Base- 

 ment Culm Measures, but while admitting that Phillips might be 

 correct in placing the Codden Hill Beds above the dark shales and 

 limestones, he thinks it best, as the lithological characteristics are 

 not permanent but recurrent on the same or nearly the same 

 horizons, to group the Basement Beds in one series rather than 

 subdivide them. 



Probably next in the upward order of succession to the Posido- 

 nomya-limestones and shales are the bluish-brown and reddish 

 shales of "Waddon Barton, near Chudleigh, and adjoining localities 

 in the Bovey Tracey district in South-east Devon ; near Bampton 

 in North Devon ; and, according to Mr. Ussher, 2 in some localities 

 south of Launceston. These shales do not seem to be always 

 developed above the dark Posidonomya-limestones and shales, and 

 in some localities they appear rather to take the place of the latter. 

 They possess a very distinct fauna, the principal feature of which is 

 the great abundance of Goniatites spiralis, Phill., of which some 

 thin layers of the shale are almost entirely composed. The only 



1 Proc. Som. Archaeol. & Nat. Hist. Soc. vol. xxxviii. (1892) pp. 120, 121. 



2 Ibid. p. 132. 



