584 THE CARBONIFEROUS LIMESTONE OF COUNTY CLARE. [Nov. 1909, 



trace the zones into the East, and the discovery of leading fossils 

 in Tian-Shan was of happy augury. The alliance of petrological 

 and palseontological characters, so strikingly illustrated by the 

 correspondence between the boundary-line adopted by the Irish 

 surveyors in the field and that based on zonal palaeontology, was 

 continually gaining in importance, and might still have some 

 unexpected application in store. 



Dr. T. F. Siblt expressed his satisfaction in learning that the 

 faunal succession of the South-Western Province was so closely 

 paralleled in the distant region of the West of Ireland. The 

 sequence described by the Author was one of exceptional interest. 

 Each zone, and almost every subzone, of the typical Avonian 

 succession appeared to be clearly defined ; while the additional 

 development of a Cyathaxonia subzone constituted an extension of 

 the typical sequence, and furnished an interesting point of agree- 

 ment with the succession in the Midland Province, where that 

 subzone formed so conspicuous a feature. The great thickness 

 of the Dibunophyllum Zone was another characteristic in common 

 with the Midland development. Special points to which the speaker 

 drew attention were, the large development of chert in the 

 Upper Zaphrentis Zone (paralleled in the Mendip area), and in the 

 Burren Limestone (paralleled in part by the great cherty series of 

 D 2 in the Midlands) ; also the occurrence of Lonsdalia duplicata, 

 an uncommon and very distinctive fossil, at the precise horizon 

 at which the same species occurred in Derbyshire, namely, the top 

 of D 2 . In conclusion, he wished to congratulate the Author upon 

 his successful investigation of a very important area. 



Mr. Cosmo Johns said that he was pleased to learn that a normal 

 Carboniferous development, so far west as County Clare, had been 

 carefully investigated. He would have liked a more detailed 

 account of the fauna which marked the base of the Visean: in 

 many parts of Britain it formed a distinct and very important 

 horizon. It would also be interesting to learn the nature of the 

 evidence on which the Author relied when drawing a line between 

 the several zones. A very desirable method of investigation would 

 be to map the more important faunal lines for comparison with a 

 map indicating the lithological divisions. He thought that caution 

 should be exercised in referring to the divisions that had been 

 made in the Belgian sequence. The tangled sections of that 

 country would best be straightened out by reference to the many 

 clear and uninterrupted exposures in Britain. 



Dr. Ivor Thomas deprecated the use of the names ' Vise'an ' and 

 'Tournaisian' at the present stage of Carboniferous Limestone 

 research, especially as the Belgian sequence had not yet been zoned 

 on the lines suggested by Dr. Vaughan. Moreover, the typical 

 Visean and Tournaisian of Belgium appeared to be only locally 

 developed. The Visean of Vise passed downwards into a mass of 

 practically unfossiliferous dolomitic rocks — the so-called ' Devonian ' 

 of certain Belgian geologists ; while the Tournaisian of the Kamur 



