JURASSIC OP THE PARIS BASIN. 



, 583 



of the Bolonian beds in the Meuse, as Hebert supposed (21) ; for, as 

 Buvignier (22) points out, the smaller quantity there visible is com- 

 posed of the lowest beds only, and not of diminished representatives 

 of all. On entering the Haute-Marne much more is seen, in fact 

 the full development, which, however, commenced near Bar-le-Duc 

 in the extreme limit of the Meuse. The Lower Bolonian will here be 

 the " Lithographic limestones " of Buvignier and the zone of Ammo- 

 nites gigas of Boyer and Tombeck, of which, after them, the Bure 

 oolite may be taken as the upper limit *. The Upper Bolonian in- 

 cludes the more fossiliferous beds, distinguished as carious, spotted, 

 and tubulous limestones, and also the lower portion of the series 

 called the zone of Cyrena rugosa, namely the porous limestones, 

 which are mostly unfossiliferous, but in places appear to contain 

 Natica Marcousana, a very characteristic Bolonian fossil. Passing 

 westwards, the tubulous limestones and higher beds are rapidly lost, 

 and the series is reduced in the valley of the Aube to the Lower 

 Bolonian and the carious limestones. These two are of longer con- 

 tinuance, and are found as fully developed and still more fossiliferous 

 in the valley of the Yonne, while they have representatives as far as 

 Bourges. In the Charente the sandy limestones near Angouleme give 

 us fair representatives of the Lower Bolonian, though with a somewhat 

 uncommon fauna, somewhat allying it to the Upper. This latter must 

 be recognized in the wide-spread limestones with Cyprina Brongni- 

 arti and other usual fossils of this horizon. Possibly representatives 

 of the Lower Bolonian exist in the He d'Oleron, in the limestones at 

 the base with A. Gravesianus ; but the great mass seen to the south 

 of the harbour of S. Denis is undeniably Upper Bolonian, with the 

 same palseontological characters as in the Charente. Neither in the 

 Orne and Sarthe departments nor in Normandy are beds so high in 

 the series reached. In the Pays de Bray the lowest Upper Jurassic 

 rocks are the Yirgulian marls ; and above them the Bolonian beds 

 are well developed. These are considered by M. de Lapparent (69) to 

 commence with his "beds with Ostrea catalaunicaf while his "upper 

 clays and lumachelles " and " compact lithographic limestones " are 

 referred to the Yirgulian. It has, however, been shown that the top 

 of the " lower clays and lumachelles " is exceedingly similar in cha- 

 racter to the base of the Lower Bolonian at Boulogne, that in the 

 north these contain the characteristic Trigonia Munieri, and in the 

 centre the lithographic limestones contain Amm. gig as, while in the 

 south, according to MM. Sasmann and Graves (39, 8), at Hodenc, a 

 locality coloured Portlandian by M. de Lapparent, the upper marls 

 (which are very thin in the north) contain Amm. gigas and Amm,. 

 Gravesianus, and are followed immediately by beds with Cyprina 

 Brongniarti. Hence it is more consonant with other localities to 

 commence the Lower Bolonian towards the top of the " lower clays 

 and lumachelles," and end it at the top of the " beds with Ostrea 

 catalaunica." The Upper Bolonian, as before noted, commences 

 with the " calcareous grit with Anomias " and continues to the top 



* Perhaps the beds at Cirly recorded by Tombeck to contain Amm. gigas 

 and A. suprajurensis, ought to be also included in the Lower Bolonian. 



