The Carboniferous Limestone of West Cumherland. 123 



material for the study of the stinicture of many of the members of 

 that ubiquitous class. Almost all genera of rugose corals found in 

 the Lower Carboniferous of other areas in the British Isles are 

 represented, and good specimens are obtainable from practically 

 the whole of the limestones. 



Fig. 1 gives the vertical distribution of the principal genera. 

 The abundance of material and mode of vertical distribution greatly 

 facilitate a study of the ontogeny, phylogeny, and the various 

 mutational characteristics of the several members of the order. 



Correlation with the Alston Moor Limestones. 

 Mr. J. D. Kendall in his j^aper^ correlates the limestones of our 

 area with the rocks of Alston Moor and Fiirness as under :— 



Yoredale 

 Eocks. 



Alston Moor. 

 /'Fell Top 



Little 



Great 



Four Fathom 



Three Yard 



Five Yard 



Scar 

 l.Tyne Bottom 



Mountain 

 Limestone 



Whileharen ( = West 



Climb.). 

 First Limestone 

 Third Limestone 



/Fourth Limestone 



Furness. 



'Yoredale Eocks 



-Fifth Limestone 



( Sixth 

 J < 



. Seventh 

 (Eed Shales 



Thick Limestone 



Eed Shales and Limestone 

 Such a correlation, however, does not suggest itself after an 

 examination of the fossil fauna. Fig. 2 gives the correlation ^ which 

 appears to be most in consonance with the fossils of the two areas. 

 The Fell Top Limestone which Mr. Kendall correlates with the 

 First Limestone has a distinctive fauna that does not find its 

 counterj)art in any of our limestones. This fauna is marked by 

 the occurrence of a coral, Aulina rotiformis S. Smith, by an 

 abundance of Dihunophyllum -yjr Vaughan and by certain brachiopods 

 that are characteristic of the highest beds of the Dihunophyllum 

 Zone in the North- West Province and in Derbyshire, such as Productus 

 aculeatus Mart, and Schellwienella radialis (Phill.). Neither Aulina 

 rotiformis nor the brachiopods mentioned have been found in our 

 area. On the other hand, there is a striking similarity between the 

 fauna of the limestone known as the Great Limestone of Alston Moor 

 and Northumberland and that of our First Limestone, as the 

 following list of corals and brachiopods which are common to both 

 shows : — 

 Dihunophyllum muirheadi 



Nich. & Thomson. 

 * KotiinckojyJiyllum niagnijicum 



Thomson. 

 *Caninia cf. sub-ibicina McCoy. 



Zaphrentis constricta R. G. Carr. 



Choetetes septosa Flem. 



[in wide spreading flat sheets] 



Aulophyllum fungites Flem. 



1 Op. cit. 



^ The approximate scale of this section is 220 feet to 1 inch. 



