T. Davidson — On Continental Geology, 165 



6. Gaedonien (Coquand), after the Gard — 



Vicarya Renauxiana, Teredo Fleuriansi. This stage is of lacustrine origin, and 

 will require hereafter to be united either to No. 5 or 7. 



7. EoTHOMAGiEN (Coquand), after Eouen — 



Ammonites Rothomagensis, A. varians, A. faleaius, Scaphites cequalis, Turrilites 

 costatus^ Pecten asper, Terebratella pectita, T. lyra, Ostrea conica, Radiolites 

 Moriom. It corresponds to the Craie Chlorite'e or Glauconieuse, to the Upper 

 Green Sand ("Warminster Sand), the C^nomanien of d'Orbigny ; Unterer Planer 

 inferieur (Greensand of Essen). 



8. Vkaoonien (Eenevier), from Vraconne in Switzerland — 



Ammonites inj^afus, Bhynchonella sulcata, Am. auritus, A. latidorsatus. It 

 corresponds to the Gault Superieur of the Swiss, to the Cambridge Upper Gault 

 or Green Sand, Flammenmergel of the Germans. 



Albien (d'Orbigny) — 



Ammonites splendens, A. mamillaris, A. Raulini. It corresponds to the real 

 Gault of Folkstone and Wissant, to the Oberer and Mittler Gault of the Germans. 



III. Lower Chalk. 



1. TJrgo-Aptien — 



1. Argiles a Plicatules — Ammonites nistts, A. Gargasensis ; Flicatula placunea., 



Belemnites semicanalictclatiis, Ostrea cequila, Terebratella Astieriana (Lower 

 Green Sand of the English geologists), Aptien of d'Orbigny, Unterer Gault, 

 Mergel, and U. G. Then of the Germans. 



2. Couches a Orbitolites — Ancyloceras Matheronianum, Flicatula placunea, Be- 



lemnites semicanaliculatus, Ammonites Jissicostatus, Nautilus plicatus, Mete- 

 raster oblongus, Fseudodiadema Malbosi, Caprotina Lonsdalii, Ostrea aquila, 

 0. macroptera, Orbitolites lenticularis. (Etage Ehodanien of Eenevier). 



3. a. Urgonien (d'Orbigny) Requienia Lonsdali, R. ammonia, Nerinea Co- 



quandi, N. Archimedi, N. gigantea, Heteraster oblongus, Ostrea aquila. 

 Nautilus plicatus, Orbitolites lenticulata, Scaphites Tranii. 

 h, Barremien (Coquand) Ancyloceras Fuvalii, A. Emerici, A. Tabarelli, 

 Terebratella Astieriana, Ostrea Leymerii. 

 a. and b. are parallel, a. represents the coral aspect, b. the littoral aspect* 

 both correspond to the Argiles Ostr^ennes. As we find them in Pro- 

 vence so is it in the Pyrenees and Spain ; there exist alternations 

 between the Aptien beds and the Urgonien, and it became con- 

 sequently necessary to form of the two a single division. The sub- 

 divisions denote a peculiar facies, a petrographical character, which 

 nevertheless varies according to the country where observed. These 

 three subdivisions correspond with the Upper and Middle Neocomien 

 of Mr. Judd, to the Neocomien Superieur of M. Cornuel. 



2. Neocomien — 



Ammonites Astierianus, A, multiplicatus, Ostrea Gouloni, 0. rectangularis, 

 Toxaster complanatus, Belemnites latus, and dilalatus. It corresponds to the 

 Marnes d'Hauterive, Lower Neocomien of Judd; Hills, of the Germans. 



3. Valengien — 



Ammonites Gervilianus, Strombus Sautieri, Fygurus rostratus. The equivalent 

 of the Wealden of England, and of the first stage of the Neocomien inferieur of 

 Cornuel. 



From the above it would appear that M. Coquand divides the 

 Cretaceous system into seventeen etages or divisions, of which nine 

 only would seem to occur in Great Britain. 



To our White Chalk he applies the term Campanien, while to the 

 upper portion only of our Lower Chalk the term Santonien is given, 

 then according to the same geologist, four divisions would intervene, 



