INTRODUCTION. 9 



In a south-easterly direction the Carboniferous sea extended across the whole 

 east and south of England, passing over the Ardennes and North Central Europe 

 to the Urals. 



Judging from the presence of similar faunas wherever Carboniferous rocks are 

 explored, it would appear that conditions of climate were fairly equable over the 

 whole of the earth in those times. Indeed, it is questionable whether the 

 differences in the various species described from European, American, and 

 Australian Carboniferous rocks really indicate variations of specific value, and are 

 any greater than might be expected in a single species of very wide distribution. 



There is a certain amount of doubt as to the true base of the Carboniferous 

 rocks in the South west of England and Ireland. This question was discussed by 

 Beete Jukes in the ' Memoir of the Geological Survey of Ireland, Explanation 

 of Sheets 187, 195, and 196,' pp. 33 — 37, who summed up in favour of the Baggy 

 Point, Brauuton, Marwood, and Pilton beds of Devonshire, and the Coomhola 

 Grits and Carboniferous Slate of co. Cork, being regarded as belonging to the 

 Carboniferous system, rather than to the Old Red Sandstone, on paljeontological 

 grounds. 



He says, p. 34, " With the exception of the shells called Cucullgea and' Curto- 

 notus,and a few other fossils which are found almost solely in the grit stones (and 

 which we may suppose, therefore, to have been sand-loving animals), and a few 

 species such as Modlola Macadami and Avicula Damnoniensis, which are found 

 chiefly in shales or slates (and appear, therefore, to have been inhabitants of muddy 

 bottoms), most of the species found in the Carboniferous Slate are also found iu 

 the Carboniferous Limestone. It is true that the limestone has many species which 

 are not found in the grits, or in the shales or slates, but it is obvious that we may 

 attribute this also to the nature of the different sea bottoms." The following 

 Carboniferous fossils occur in the debatable beds : 



Fenestella antiqua. 

 Athyris ambigua. 

 Productus scahricuhts. 

 Mhynchonella pleurodon. 



Spirifera cuspidata. 



— striata. 

 StreptorTiynchus crenistria. 

 Terehratula hastata. 



Of these he says, they " range throughout the Carboniferous Slate as they do 

 throughout the Carboniferous Limestone, occurring in the grits and slates side by 

 side with the fossils that are peculiar to those beds." Not only, indeed, do fossils 

 which are commonly found in the Carboniferous Limestone occur in the Pilton 

 beds of Devonshire, classed as Upper Devonian, but even in the Lynton Slates, 

 Lower Devonian, i^e»C6'fe//a antiqna and CJwnetes Hardrensis, and in the Ufracombe 

 beds. Middle Devonian, Fenestella antiqua, Ehynchonella pugnus, B. pleurodon, and 

 Stveptorhjnclms crenistria occur, together with a number of forms not known in 



2 



