482 PKOCEEDINGS OP THE GEOLOGICAL SOCIETY. [May 20, 



measurements of all the beds, and I find that Lingula occurs in great 

 quantities in the olive shales, while the calcareous sandstones are full 

 of Cucullcea, Belleroplion, Orthoceras, &c. The whole must have been 

 accumulated in a very shallow sea. 



Thence southward, undulating beds of slate with many sandstone- 

 bands contain all the fossils of the Pilton group. Top Orchard 

 quarry, near Pilton, is a favourite locality. In beds below this, and 

 very near the base of the group, I found a single specimen of Cur- 

 tonotus, which is somewhat important, inasmuch as this genus, both 

 in Pembrokeshire and in South Ireland, belongs only to the beds which 

 underlie the true Carboniferous slate. Spirifer disjunctus, Productus 

 Cliristiani, i. e. prcelongus, Avicula subradiata, and Athyris concen- 

 trica are still the common fossils. 



But nearer Barnstaple these Pilton beds begin to trough small 

 patches of a barren softer slate, which is only seen well developed 

 south of Pilton, and occupying the lower ground east and west of 

 Barnstaple. Another anticlinal roll throws in a trough of it about 

 Ashford and Heanton Punchardon, and it is fossiliferous on Ashford 

 Strand. South of the river it may be seen along the course of the 

 railway, skirting the marshy ground, and there is a good section of 

 it at the railway-station. 



It is extremely difficult to say precisely where the Pilton group 

 ends and this group of shales begins ; but the absence of sandstone- 

 bands and the presence of only Carboniferous species show suffi- 

 ciently the reality of the change. Strophalosia caperata, var. mem- 

 branacea, is occasionally present, but not the ordinary variety. It 

 is associated with Spirifer laminosus, S. cuspidatus, Streptorhynchus 

 crenistria, Ghonetes Hardrensis, Athyris Roissyi, Belleroplion decus- 

 sations, Productus costatus, P. Martini, Orthis Michelini, Venus par al- 

 lela, Phillips, Spirifer ovalis (small), S. bisulcatus, Phillipsia semini- 

 fera, and many others. But these are enough to show that we have 

 •passed from the sandy Pilton group to the true Carboniferous Slate. 

 The Encrinites are exceedingly common : but those stems I have 

 been able to compare with Pilton species are not identical, while all 

 the peculiar Pilton species are quite absent. Yet the general aspect 

 of the Encrinites, Fenestella, striated Spiriferi, Ghonetes, &c, is so 

 much that of the Pilton group just underlying, that it was only by 

 great good fortune I made out the troughs of this newer formation, 

 lying among the contorted beds of the Pilton group. 



South of Barnstaple we are indeed fairly in the Carboniferous 

 series. Along the course of the Fremington Pill I found, in 1854, 

 shaly beds overlying these, still with Mountain-limestone fossils. 

 The Productus Cora, or rather P. Scotica*, as it ought to be called, is 

 a fossil not yet detected even so low as the Limestone-shale. But 

 how far upward the Mountain-limestone extends until it is capped 

 by the Millstone-grit of Coddon Hill it would be out of my province 

 to discuss here. It is more to the purpose to mention briefly the 



* Sowerby's type-specimens of P. Scotica are identical with the shell D'Orbigny 

 afterwards called P. Cora, and M'Coy P. corrugata. 



