Vol. 5 I.J RADIOLARIAN ROCKS IN THE LOWER CULM MEASURES. 667 



Fig. 8. Proetus, sp. b. An imperfect specimen, enlarged 3 diameters. Combe 



Wood Quarry, Dear Barnstaple. 

 Figs. 9, 9 a. Productus concentrlcus, Sarres. Cast of the ventral valve. Na- 

 tural size, and enlarged 2 diameters. Hannaford Quarry. 

 Fig. 9 b. Productus concentrlcus, Sarres. A specially wide form. Natural size. 



Hannaford Quarry. 

 Figs. 10, 10 a. Productus plicatus, Sarres. Cast showing traces of spines. 



Natural size, and enlarged 2 diameters. Hannaford Quarry. 

 Fig. 10 b. Productus plicatus, Sarres. Cast of the ventral valve, enlarged 2 



diameters. Hannaford Quarry. 

 Figs. 11, 11a. Productus, cf. Icevipunctatus, Sarres. Internal cast of the ventral 



valve. Natural size, and enlarged 2 diameters. Hannaford Quarry. 

 Figs. 12, 12 a. Chonetes rectispina, von Koenen. Natural size, and enlarged 2 



diameters. Hannaford Quarry. 

 Fig. 12 b. Chonetes rectispina, von Koenen. Cast of the dorsal valve, enlarged 



2 diameters. Hannaford Quarry. 



Figs. 13, 13 a. Chonetes Laguessiana, de Koninck. Cast of the ventral valve. 

 Natural size, and enlarged 2 diameters. Hannaford Quarry. 



14, 14 a. Leptcsna analoya, Phill. Cast of valve. Natural size, and en- 

 larged 2 diameters. Hannaford Quarry. 



15, 15 a. Orthotetes crenistria, Phill., sp. Cast of the brachial valve. 

 Natural size, and enlarged 2 diameters. Hannaford Quarry. 



16, 16 a. Spirifer, sp. Internal casts of the dorsal or brachial valve. 

 Natural size. Hannaford Quarry. 



17, 17 a. Athyris, sp. Casts of the interior and exterior of the ventral 

 valve. Natural size. Hannaford Quarry. 



Fig. 18. Pleurodictyum Dechenianum, Kayser. Cast of a small specimen. 

 Natural size. Hannaford Quarry. 

 18 a. The same. Cast of the basal portion of a larger specimen, showing 

 the arrangement of the corallites. Natural size. Hannaford Quarry. 

 18 b. The same. Some of the corallites, enlarged 3 diameters, showing 

 the disposition of the connecting pores. 

 Figs. 19, 19 a. Ckidochonus Michelini, M.-Edw. & Haime. Cast of a single 

 corallite and pedicel, showing vertical rows of pores in the calice. 

 Natural size, and enlarged 3 diameters. Hannaford Quarry. 

 Fig. 20. Petraia, sp. Cast of the interior of the calice. Natural size. Hanna- 

 ford Quarry. 

 20 a. The same. The base of the cast, showing the disposition of the 

 septa and the rows of minute pores on either side of them. Enlarged 



3 diameters. 



Discussion. 



The Chairman (Mr. "W. H. Hudleston) remarked that such a 

 paper as this proved that the subject of British geology was by no 

 means exhausted. Notwithstanding the attention which had been 

 paid to the several members of the Carboniferous system in Devon- 

 shire, the existence of a thick series, mainly of organic origin, on 

 the horizon of the ' Codden Hill Grits ' had hitherto been unsuspected. 

 The correlation of these with the Millstone Grit had long ago been 

 considered doubtful by him, but it had the sanction of authority. 

 Besides the palseontological importance of a discovery like this, 

 such a well-marked horizon might be useful in determining boundary- 

 lines in areas where the Carboniferous and Devonian were much 

 mixed up, as in the Tavistock district. 



The Rev. G. F. Whidborne said that he had listened to the paper 

 with interest, as he had visited the Codden Hill quarries last summer 

 with Mr. J. G. Hamling, and had collected a number of fossils from 



