FAUNAL SUCCESSION IN THE LOWER CARBONIFEROUS LIMESTONE. 109 



The highest beds, with Prod, longhpinus, can be assigned to 

 Upper D. 



III. The Ourthe Valley (Comblain-au-Pont). 



Two types of Tournaisian sequence are exhibited side by side : — 



(1) Bivage to Liotte. 



The upper part of the transition series apparently contains a 

 Carboniferous fauna. 



The shales that succeed certainly contain Spiriferina, but the 

 accompanying fauna suggests a level in Z higher than ft. [Similar 

 shales underlie ' petit granit ' at Maredsous.] These shales are 

 overlain by Z-y and the Caninia beds of 1 . 



(2) N. of Comblain-au-Port. 



The 'petit granit' of the Ourthe, Z -y, is succeeded by 

 'laminosa dolomites,' C 1( similar, faunally and lithologically, to 

 the beds of the same phase in the Bristol area. 



These dolomites are capped by a calcareous conglomerate 

 (Breche de Comblain-au-Pont), recalling tile megastoma-con- 

 glomerate of County Dublin. 



IV. Dinant District (Gorge of the Meuse : Hastiere, Dinant, 

 Yvoir) — the type sections of the Dinantian. 



The correlation table gives the main points in the comparison 

 between the complete sequence of this district and that of the 

 Avon. The following notes may be added: — ■ 



' Calcaire d'Yvoir ' and ' Petit Granit ' (when present) must 

 both be included in Z-y. 



The Calcaire de Leffe of Dorlodot must be correlated with the 

 top of the Tournaisian by relative position only, since it is practi- 

 cally unfossiliferous. 



The highest black limestones and shales, discovered by 

 Mr. Delepine between Dinant and Yvior, contain a well-marked 

 Upper D fauna. 



V. The Waulsortian. (The District West of Dinant : Hastiere, 

 Waulsort, Maredsous, Sosoye.) 



The levels suggested for the various Brachiopod beds are 

 deduced from 



(a) the relative predominance of Spirifer and Productus. 

 Spirifer predominant indicates Tournaisian, as in the ' r6cif ' of 

 Maredsous. 



(b) The occurrence of ' Visean species ' of Productus, such as 

 P. margaritaceus, e.g., at Sosoye. 



(c) Stages of structural development. 



N.B. — Care musi be taken to eliminate certain species that are appa- 

 rently persistent throughout the Lower Carboniferous and that 

 recur at every renewal of similar conditions, e.g., Pvgnax acumi- 

 nata, var. plicata, and Pugnax pugnus among Brachiopods and 

 Amplexus coralloides among Corals. 



