JURASSIC OF THE PARIS BASIN. 



527 



ravine : and here, high above the cement-stones, perhaps 200 feet, 

 we find a fossiliferous zone, similar to that at Saucourt, belonging 

 to the compact limestones above the Dicer as-beds. This contains 

 Area lineolata, Mytilus longcevust, Trigonia Etalloni, Avicula obliqua, 

 Pecten suprajurensist, and Rliynchonella pinguis. Towards the 

 top of the quarry the limestones become chalky. These great masses 

 of course occupy the country for several miles ; and thus we find this 

 same fossiliferous zone three miles to the north atBayel. Here, too, 

 the Rhijnchonella-'bed lies at the base, and the upper part is chalky. 

 Cladophyllia occurs here and there ; and in addition to the same 

 Trigonia and Avicula, there are Pecten vimineusl, Cyprina callosa, 

 Bom. ?, Terebratula tetragona, and Cidaris Smitliii. Traced still 

 further upwards, the rocks become lithographic and unfossiliferous. 

 The whole of this mass was considered Astartian by Leymerie ; and 

 hence he gives 320 feet as its thickness ; but it plainly represents 

 every thing which lies between the Oxfordian and Pterocerian. 

 The next recognizable beds are irregular somewhat marly lime- 

 stones, with Pteroceras Ponti and Mytilus aeinaces. In such a mass 

 it is difficult to recognize Astartian beds ; but it seems probable that 

 some part at least of the lithographic limestones belong to them ; 

 and hence the overlying beds, which are irregular in character, and 

 contain one of the characteristic fossils, are the best representatives 

 of any thing that could be called Pterocerian that has been hitherto 

 seen. On the north of Bar-sur-Aube the marls with Exogyra 

 virgula are well exposed, but do not yield many fossils, the chief 

 noticed being Pleuromya tellina. This portion of the series pos- 

 sesses but little interest, but is followed by the "Portland" litho- 

 graphic limestones similar in character to those at Joinville, and 

 containing a plicatiloid Ammonite like A. biplex. Above this 

 is seen, near Bossancourt, another important Oolite in this series. 

 It is the one which, in the Haute-ALarne, is called the Bure 

 Oolite* here developed to a bed of considerable importance, more 

 than 6 feet in thickness, and worked in underground mines for 

 building-stone. It is singularly free from fossils ; but below it are 

 some dirty-coloured oolites, with Amm. suprajurensis and small 

 ovsters ; whilst above are thin-bedded rather chalky limestones, 

 with oysters also, and the following fossils — Cardium Dufre- 

 noycum, Cardium Verioti, and Trigonia truncata. These pass into 

 varying limestones, amongst which are the beds containing great 

 branching earth-filled hollows, hence known as the carious lime- 

 stones. They are well developed — partly chalky, partly rubbly — 

 all the way to Trannes, where a large quarry shows the last of the 

 jurassic rocks in this district. In these beds, which would probably, 

 if searched, reveal a good fauna, occurred Lima suprajurensis, L. bo- 

 loniensis, Pecten suprajurensis, Interna fragosa, Terebratula subsella 

 (var. minor), and teeth of Lepidotu.s. We here therefore do not see 

 beds so far up in the series as those of the AEarne valley, no repre- 

 sentatives of the spotted limestones or of the vacuolar oolite being 

 preserved ; but the lower portions seem to become more and more 

 fossiliferous as we pass westward. 



