JURASSIC OF THE PARIS BASIN. 



539 



KlMMERIDGIAN. 



Limestone of Barrois. 

 Virgulian marls. 

 Astartian limestone. 



A. Marls and nodular limestones. 



B. Nerinrean Oolite. 



C. Eucoidal marls and limestones. 



CORALLIAN. 



Upper lithographic limestones with Amm. achittes. 



D. Limestone with Pinna. 



E. Compact limestones. 

 Chalky limestone of Bourges. 

 Lithographic limestones. 



Sponge limestones, vnih. Amm. marantianus, A. bimammatus, and^. plicatilis. 



The first traverse in this department is in the neighbourhood of Bour- 

 ges, where the succession has been already well studied and described. 

 Prom 3 to 6 kilometres north of the city the Virgulian marls appear, 

 overlain to the north by lithographic limestones, belonging doubt- 

 less to the so-called Portland, and at the hill immediately outside of 

 Bourges the different Astartian beds are seen. The highest are 

 earthy limestones, partially lithographic and often extremely marly. 

 The characteristic fossils are large examples of Ceromya excentrica and 

 Pholadomya rostralis, Terebratula subsella and Plectomya rugosa; 

 Natica Royeri also occurs. The next seen are a few feet of rubbly beds, 

 becomiugvery oolitic below, and more like the corresponding rock in 

 the Boulogne area than any yet seen. It is the jNTerinsean Oolite of 

 the authors quoted, aud contains Nerincea Desvoidyi?, Trichites 

 Sctussurei, Terebratula subsella, abundance of T. Leymerii, Rhyn- 

 chonella pinguis ?, Pholadomya rostralis, and Trigonia Baylei, the 

 last-named forming an interesting connexion with the rocks at Havre. 

 The lower fucoidal marls have not been examined ; but from the list 

 of fossils quoted, among which may be noted Mytilus perplicatus, 

 Plectomya rugosa, Terebratula subsella, and RhyncJionella pinguis, it 

 is obvious they form part of this series. On the south of Bourges a 

 different group of rocks occur, the upper part being lithographic, 

 unnecessarily divided into two parts. The fossils are few, and 

 belong to Pinna obliquata (a broad species), Lucina cf. imbricata, 

 and Terebratula ? tetragona. These are of considerable thickness, and 

 are underlain by beautiful white limestone, which betrays its origin 

 when closely examined. It is then seen to be an exceedingly fine 

 rubble, having here and there larger grains, and becoming almost 

 like the Diceras-beds, to which it corresponds, and into which it 

 is said to change at Sancerre. Terebratula cincta and RhyncJionella 

 coraMina are extremely abundant. Lima Iceviuscida, L. rigida, 

 and Corbis gigantea were also observed. In the old quarries of the 

 Chateau, what are probably lower beds are seen through 20 feet and 

 more. Here are abundance of massive corals, with Cidaris flori- 

 gemma and many shells, but fewer Brachiopoda. This, then, is the 

 true Coral Bag as usually seen, and corresponds to the white lime- 

 stones of Tonnerre and Augy. Below this the beds have not been 

 examined, as they are stated to consist of a uniform mass of litho- 



