260 Dr. Wheelton Hind — Zones of the Carboniferous. 



Productus Edelburgensis, Phillips, was regarded by Davidson as 

 a variety of " P. giganteus in which the valves are more coarsely 

 striated with interspaces of almost equal or greater width." Phillips 

 gives his localities as Addleburg, Bolland, Fountains Fell, but 

 P. giganteus he states is from Aldstone Moor and Hawes. I have 

 found the latter abundantly in beds of Yoredale series in Teesdale. 

 Of course Davidson may have been in error in supposing that 

 P. Edelburgensis and P. giganteus wei'e the same species, but it 

 would be advisable to prove conclusively that such was the case 

 before the two forms are declared to be typical of different horizons. 



In North Staffordshire P. latissimus and P. giganteus occur 

 together in Carboniferous Limestone at Narrowdale, and in Derby- 

 shire at Park Hill, near Longnor. In Cheshire, at the Astbury 

 limestone quarry, and in the last two localities, Chonetes papilionacea 

 also occurs. So that in these localities, at any rate, these three 

 forms cannot be said to be characteristic of different horizons. In 

 these localities P. latissimus and P. giganteus are very abundant 

 indeed, with a very rich fauna of characteristic Lower Carboniferous 

 facies. 



P. giganteus also occurs abundantly in the Redesdale Limestone, 

 Northumberland, a bed which is recognized as the base of the 

 Upper Limestone series in that county, and supposed to correspond 

 to the Yoredale series of Yorkshire. Both Productus giganteus and 

 P. latissimus are quoted by Lebour (" Geology of Northumberland," 

 p. 116) as occurring together in the Great and Four-fathom Lime- 

 stones of Lowick, which occur above the Bedesdale Limestone and 

 high above the Melmerby Scar Limestone. P. giganteus also occurs 

 in the Pipecross Limestone in the Carbonaceous or Lower Limestone 

 series of Northumberland. 



In the lists of fossils, arranged stratigraphically, contained in 

 the Memoirs of the Geological Survey, Scotland, explanations of 

 Sheets 23 and 31, Productus latissimus and P. giganteus are shown to 

 occur together at many horizons, and to have exactly the same vertical 

 range. In the palaiontological notes to the memoir of the Irish 

 Survey, "The Geology of the Country round Dublin," P. giganteus 

 is stated to occur in three different beds with Chonetes papilionacea. 



Chonetes papilionacea occurs abundantly in the limestone of 

 Cauldon Low, North Staffordshire, one of the highest beds of the 

 deposit, and probably a much higher horizon than the beds of 

 Waterhouses and Narrowdale, where P. giganteus and P. latissimus 

 occur. Neither Chmtetes septosus, as far as my experience goes, nor 

 any other coral occurs at Cauldon Low, which is characterized by 

 abundance of the rare P. humerosus, and the stone itself has peculiar 

 and distinctive lithological characters. Davidson quotes Chonetes 

 papilionacea from Otterburn, but I can find no authenticated 

 occurrence of this species in Northumberland. 



Under such circumstances, therefore, the value of the fossils 

 mentioned as distinctive of zonal succession can hardly be 

 sustained, as the majority of them occur at more than one horizon, 

 and are found in other localities not by any means in the vertical 



