JUBASSIC OF THE PARIS BASIN". 



573 



St. Mihiel we have a thin bed below the coral-growth, which is best 

 called Coralline Oolite ; and it is probably the end of the great lime- 

 stones of Creue, which also will be placed as such. Buvignier has 

 himself (22) recognized that the Coral Eag of St. Mihiel is no other 

 than that of Verdun, and it is only one facies of the beds of this age. 

 The Supracoralline division retains its former character, but begins to 

 have true Diceras-beds on the top, especially in the south (21). In 

 the extreme south the Coral Eag develops into a very thick mass, which 

 is very rubbly and fossiliferous towards the base, with Cidaris flori- 

 gemma &c, surmounted by white chalky limestone, and finally by 

 compact limestone beneath the Astartian beds ; so that here the 

 distinctions of the two parts of the Corallian are less marked. In 

 the Haute-Marne, at Eeynel, in the east, the rubbly Coral Eag occu- 

 pies the base, and more compact limestone lies above it (55), with a 

 development of the Diceras-beds above. In the valley of the Eognon 

 there is a band of disaggregated Oolite at the base (19), then a fine 

 development of the Eag, and a magnificent display of the Supracoral- 

 line beds in the form of pisolites with Biceras, with compact and 

 oolitic beds associated, up to the more marly Astartian beds. In the 

 valley of the Marne the Supracoralline Diceras-beds have become the 

 summit ; and beneath come the massive coral- growths with Cidaris 

 Jtorigemma, occupying a great thickness, and having below them 

 massive limestones, which might be called Coralline Oolite ; but as, 

 according toEoyer(12), they have rubbly rag below them at Soncourt, 

 they must be placed as a development of the Coral Eag. Passing 

 west towards the Aube, the Diceras-beds become more restricted, and 

 confined to the upper part, as at La Mothe, while the coral-growth 

 or rubbly beds beneath lose their character, or remain as shelly lime- 

 stones only. On reaching the valley of the Aube itself, all is united 

 in an undistinguishable mass of limestone, with only a shelly repre- 

 sentative of the Supracoralline beds ; and Astartian and Corallian 

 form one massive, lying on Oxfordian marls at Clairvaux, and 

 covered by Pterocerian marls near Bar-sur-Aube. Travelling west 

 to the valley of the Laignes, new developments arise. The thin shelly 

 band is replaced once more by Diceras-beds of considerable thickness, 

 and the beds below put on a characteristic form at the base ; for 

 below a mass of compact and false-bedded limestone comes a rubbly 

 mass of coral-growth, full of the shells which usually accompany it, 

 though Cidaris florigemma was not noticed. This again might be 

 called Coralline Oolite, but that it is believed to develop into Coral 

 Eag later on. In the valley of the Armancon this lower shelly mass 

 has again dwindled down to a narrow band ; so that it was left to 

 Cotteau, or rather to ILLetteron (43), to discover it, filled with corals 

 and the usual shells and echinoderms, underlying the lithographic 

 limestones. This discovery seems to give the coup de grace to the 

 idea of the latter being Upper Oxfordian (25). They are, in fact, 

 the continuation of the compact limestones of the Laignes valley ; and 

 in various beds contain a Corallian fauna, the uppermost of which, 

 met with byM.TIebert near Angy, seems to have led him (31)to place 

 the Emit of the Oxfordian too high, i. e. above instead of below the 



