660 BE. G. J. HINBE AND ME. HOWAED FOS ON [Nov. 1895,. 



shales. They thus present more points of comparison with the 

 Upper than with the Lower Culm of this country. In these regions 

 the siliceous or Kieselschiefer beds of the Lower Culm are either 

 not developed or they have been denuded away, since fragments 

 of them are not infrequently found in the conglomerates. At 

 Wildenfels in Saxony, 1 moderately thick limestones occur in the 

 Lower Culm, which contain Endothyra and corals common to the 

 Carboniferous Limestone, similarly to the limestones at Canonsleigh, 

 etc., in North Devon. 



There are no rocks elsewhere in the British Isles which show 

 any close relationship to the radiolarian cherty and shaly beds of 

 the Lower Culm Measures. Siliceous organic rocks 2 of considerable 

 thickness do indeed occur in the Yoredale series of the Carbon- 

 iferous, in Yorkshire, Lancashire, North Wales, and Ireland, and 

 some of them have been compared by Prof. Phillips, with the cherts 

 of Codden Hill ; but microscopic examination shows that they are 

 composed of sponge-remains, and no radiolaria have as yet been 

 recognized in them. 



The macroscopic fossils which occur in the Radiolarian (Codden 

 Hill) Beds are either identical with or closely similar to species found 

 in the Carboniferous Limestone of Yorkshire, Scotland, Ireland, and 

 Belgium ; many of them are present in the Lower Culm Beds of 

 Germany, and they indicate that these radiolarian beds represent 

 the Carboniferous Limestones of other portions of the British Isles. 



The relationship of the Waddon Barton Beds with trilobites and 

 Goniatites spiralis, and the dark Posidonomya-shales and limestones 

 of Devon, etc., to the Lower Carboniferous (or Culm) of Westphalia 

 and the Harz was pointed out some years since by Dr. Henry 

 Woodward 3 ; that of the Radiolarian Beds of Codden Hill to the 

 Kieselschiefer with radiolaria of the same districts is of a still closer 

 character. 



XL SlJMMAEY AND CONCLUSIONS. 



The main fact brought out in this paper is the presence of a 

 series of organic siliceous rocks, some of a very hard, cherty charac- 

 ter, others platy, and yet others soft, incoherent shales, which are 

 developed in the lower portion of the Culm Measures of Devon T 

 Cornwall, and West Somerset. These rocks can be traced along, 

 and a short distance within, the line of the boundary between the 

 Upper Devonian slates and shales and the conformably succeeding 

 Culm shales from a few miles west of Barnstaple, North Devon, to 

 Ashbrittle, near Wellington in West Somerset, where the Culm 

 Measures disappear beneath the New Bed rocks. On the southern 

 margin of the synclinal trough of the Culm Measures the same rocks 

 are shown from near Boscastle, on the coast, up to and beyond 



1 K Dalmer, Zeitschr. d. Deutsch. geol. Gesellsch. vol. sxxvi. (1884) p. 379. 



2 ' Brit. Pal. Sponges,' Pal. Soc. vol. for 1887, pp. 98-103 ; Geol. Mag. 1887 r 

 pp. 435-446. 



3 'Brit. Carb. Trilobites,' Pal. Soc. 1883-84, p. 63. 



