572 



J. F. BLAKE ON THE UPPER 



that the two series are perfectly separate by their fossils. The 

 latter supposition we may dismiss, as it is exceedingly improbable ; 

 and it has been shown (p. 529) that in theAube several such apparent 

 junction-lines occur, one above the other. On the other hand, Tom- 

 beck's statements appear to be vitiated by his including the Oolite of 

 La Mothe in the Astartian, instead of associating it with the Diceras- 

 beds ; and if this rectification were made, we should find one palaeon- 

 tological distinction indicated by himself — namely, that while the 

 Corallian contains the zone of Cardium corallinum, the Astartian con- 

 tains that of Terebratula humeralis. Admitting, however, that the 

 actual line may be rather arbitrary, and that some Corallian forms 

 occur above it, and even Oxfordian ones, if Ammonites marantianus 

 be truly recorded, yet if it be drawn not far above the Diceras-beds 

 and ther equivalents a change is soon perceived after the line is 

 ' passed, as will be shown in the sequel We shall then have three 

 subdivisions in the Corallian series, which may or may not be deve- 

 loped in any particular locality, and the distinctness of which may often 

 be lost, but which are nevertheless sufficiently constant to make it 

 important to recognize them. The upper division, or " Supracoral- 

 line," almost wants a better name than it has received. Its most 

 remarkable form, the Diceras-beds, would almost induce us to apply 

 that name, but that the form is too local. The term " Supracoralline " 

 is applicable in the great majority of cases ; but the beds must not be 

 supposed to be always above the actual coral-growths. The middle 

 division, or " Coral Bag," is so called to denote the more common 

 position of the Astreean corals, generally associated with Gidaris 

 florigemma, though this portion may be without such corals, which 

 may occur above it instead. And the lower division, or " Coralline 

 Oolite," represents those limestones which lie in certain places above 

 the best representative of the Upper Oxfordian in the district, and 

 yet below the beds identified as Coral Rag : it is a division which in 

 most districts may be ignored. 



"We must now trace these beds in their range. In the Ardennes 

 we find, immediately above the Ferruginous Oolite, a comparatively 

 thin bed of crystalline coralliferous limestone, with Gidaris flori- 

 gemma, which may be recognized at once as the Coral Rag. It is sur- 

 mounted by the magnificent limestone of Novion, in which Gidaris 

 florigemma is rare, if present, but which contains Gardium corallinum 

 and some Dicerata. These, though full of corals, are the Supracoral- 

 line beds, becoming oolitic above, and affording no well-marked upper 

 limit. On entering the Meuse we immediately find the Coral Rag to 

 have increased, and to have developed various forms, such as oolites 

 and crinoidal limestones. There is, however, no regularity in these 

 minor beds, since near Yerdun the crinoidal limestones are beneath 

 coral-growth, whereas near St. Mihiel they cap it. Near Yerdun 

 some shell-beds are found which might be called Coralline Oolite. 

 The Supracoralline beds are much thicker. In fact, if we are to keep 

 the Astartian beds at all comparable to each other, and to include 

 all rocks of the Diceras-bed type in the Corallian, we must absorb 

 into the latter a considerable portion of Buvignier's Astartian. At 



