JURASSIC OF THE PARIS BASIN. 



533 



will occupy the place of the compact and " levique " limestone of 

 Biceys, if we find above it the representative of the Diceras-beds. 



Above the lithographic limestones comes an enormous mass of 

 white chalky limestone, seen on the right bank of the Armancon be- 

 tween Commissey and Tonnerre, and on the left bank at the well- 

 known quarries of Angy and Tonnerre. The limestone of Angy is 

 celebrated for its fossils, which occur in profusion and in admirable 

 preservation. A face of 50 feet is worked, the rock being more sandy 

 towards the base, and having masses of Septastrcea, large Montlivaltioe, 

 Triehites Saussurei,Diceras sp., Rhynchonella matronensis, Terebratula 

 maltonensis, and Cidaris, apparently not C.florigemma. As this is the 

 " White coral limestone " of Leymerie and Baulin, we find it credited 

 with 300 feet of thickness. This it might well be judged to have from 

 the hills in which it occurs ; but it is not again well seen till the 

 great quarries near Tonnerre are reached ; and here it has a 60-feet 

 face, which contains a different and higher portion, remarkable for 

 the great masses of banded flints which lie more or less in lines. 

 These are Nos. 7 to 15 of Cotteau's section (34) and contain many 

 unusual Echinoderms. We here also find the overlying rocks, 

 which are, first, a solid block of 10 feet with rolled nodules and a 

 few specimens of Diceras and Rhynchonella pinguis, and next some 

 nodular and coralliferous beds. The corals are rolled and not in situ 

 (No. 56 of Cotteau). Next comes a coarse oolite, and then another 

 rabbly bed with massive corals, Rhynchonella pinguis, Terebratula 

 Leymerii, and many other fossils, but no sign of Cidaris fiorigemma 

 (No. 24: of Cotteau). On the opposite side of the river no good 

 exposures of the white limestones occur at present; but Cotteau 

 describes an important quarry, called " Voeeuses," which contains, 

 amongst other fossils, Cardium corallinum, Glypticus hieroglyphicus, 

 and Cidaris fiorigemma. The upper part, however, is seen about 2 

 kilometres south of Tonnerre, containing but few fossils, but in 

 parts composed of white rubble of exactly the usual character. It is 

 plain, therefore, that all this mass must be considered a develop- 

 ment of the Diceras-beds of Biceys, in which the peculiar character 

 is less regularly marked, and the fossils are therefore somewhat 

 different. On this side of the river other quarries show rubbly beds 

 above, then sublithographic stone, and then another rubble-bed 

 full of Terebratida Leymerii, which Hebert (31) regards as the base 

 of the Astartian, though we have seen near Gye that there may be 

 several such overlying each other. Above comes a coarse brown 

 oolite, which may, or may not, be the same as that seen on the west 

 of the river. In any case the sequence on this side matches very 

 well with the Gye section, in which also rubbly beds with T. Ley- 

 merii were overlain by oolite. The upward succession is of no 

 particular interest here ; but the lithographic stones which overlie 

 the oolites gradually become more chalky, and finally yield Exogyra 

 virgula and Pholadomya acuticosta, beyond which the beds have 

 not been traced, as they are better known near Auxerre. 



The next traverse is up the valley of the Yonne, where it is best 

 to commence with the uppermost beds. It has been seen that 



