566 ME. J. A. DOUGLAS ON THE [Nov. I909, 



marked a break in the succession, are represented in the Mendips 

 by fossiliferous limestones exhibiting a complete transition from the 

 Tournaisian fauna to the Yisean. In County Clare, on the other 

 hand, although these beds afford abundant evidence of the existence 

 of relatively shallow-water conditions and at the same time are 

 the most fossiliferous of the whole sequence, the fauna which they 

 contain is, on the whole, distinct from the Tournaisian below and 

 the Yisean above, and seems to bear a marked resemblance to that 

 of M. Edouard Dupont's Waulsortian Phase of Belgium. 



The correlation of these beds with the Syringothyris Zone of 

 Great Britain is, however, based on the following points, and a more 

 detailed comparison with the Belgium sequence will be given below : — 



1. These beds occur immediately above the maximum of Zaphrentis 



Jeonincki, Michelinia favosa, Caninia cornucopia, and Campophyllum 

 cylindricum (horizon 7). 



2. They are succeeded by beds containing the earliest Clisiophyllids and 



Lithostrotion, associated with a typical S t fauna. 



3. Syringothyris cuspidate, the zonal index of the Mendip area, attains its 



maximum development in this zone. 



4. Both in County Clare and in the Mendips there is an abundance of 



large Euomphali at this horizon (Euomjihalus pentangulatus). 



The main differences in the faunal succession are, of course, due 

 to the entirely distinct conditions under which the deposits in the 

 two areas were 1l. . down ; and it is hardly necessary again to 

 emphasize the predominance of a molluscan fauna at this horizon in 

 County Clare, as also the entire absence of corals with the exception 

 of Amplexus. 



This type of deposit seems to extend over the greater part of 

 Central Ireland, occurring in Limerick, Queen's County, Kildare, 

 etc. Dr. Yaughan informs me that there is a similar development 

 of the Syringothyris Zone at St. Doolagh's (County Dublin). 



Note on the Comparison of the Syringothyris Zone, as 

 developed in County Clare, with the Waulsortian 

 Phase of Belgium. 



A preliminary comparison of the British Carboniferous succession 

 with that of Belgium was given by Dr. Vaughan in his paper on 

 the Bristol area, and he, I believe, contemplates further work on this 

 subject. I shall, therefore, not attempt here to give more than a 

 brief outline of the points of resemblance, both pakeontological 

 and lithological, which exist between the uppermost beds of the 

 Lower Avonian (the Syringothyris Zone) as developed in the West 

 of Ireland, and the deposits of the Waulsortian Phase of Belgium 

 (Etage II of M. Edouard Dupont). 



