204 T. Davidson — On Continental Geology. 



Nevertheless, in a letter I recently received from M. Leymerie, of 

 Toulouse, I am informed that the Cretaceous system in the Depart- 

 ments of the Aube and Yonne can be divided into — 1. Neocomien ; 

 2. Aptien; 3. Gault ; 4. Lower Chalk; 5. Middle Chalk; and 6. 

 Upper Chalk ; and that he does not consider so complicated a divi- 

 sion of the system as that proposed by M. Coquand will be found 

 necessary, when the great or general characters of the period have been 

 generally considered. He likewise reiterates the opinion already 

 expressed by M. Coquand and others, namely, that it is not possible 

 to maintain the Aptien and Urgonien as distinct stages, since they 

 have been found to alternate. He divides the Cretaceous formations 

 in the Pyrenees into TJrgo-aptien, Senonien, and Garumnien, and will 

 shortly publish, along with his detailed geological map of that por- 

 tion of France, a complete description of the different divisions into 

 which he has considered it desirable to map out the system.^ 



In the Bulletin de la Societe Vaudois des Sciences Naturelles, vol. 

 ix., p. 204, 1867, M. E. Eenevier proposes the following scheme of 

 classification, and on my recent visit to Lausanne, I requested him 

 to add some further details, and a correlation with the same forma- 

 tions in England, which I now reproduce. 



' Mr. Tombeck, Professor of Geology at the Lycee Bonaparte in Paris, has also 

 devoted considerable attention to the Cretaceous formation, as displayed in the de- 

 partment of the Haute -Marne, and he has favoured me with the following notes. 

 "My table differs from that published by M. Cornuel merely in some unimportant 

 details." 



Albien. ( 1. Clays of the Gault. 



(. 2. Green bands. 

 3. White Sands. 

 A J.- _ 3 ^- Clays with Plicatula (argiles a Plicatules), upper, 



ii-ptien. < p. -.v^iri/ii. 



5. „ „ middle. 



,, ,, lower. 



r 7. Eed bed. 

 Urgonien. •] 8. Oolitic iron. 



(. 9. Dotted sandstone and marbled rose-coloured clay. 



r\0. Clay, with oysters, (argiles ostreenne). 

 Neocomien 3 H- Yellow clayey marl. 



J 12. Limestone with Spatangus (Calcaire a Spatangues). 



(.13. Blue marl. 



r 14. White Sands. 



Valangien. \ }^- ^^/^S^i^o^^ Sands. 

 ^ ^ IG. Geodique ore. 



(. 17, Blackish clayey marl. 



" The beds in which I have met with Brachiopoda are 5, 6, 11, 12, 13, 16, and 17, but 

 they are very unequally distributed. In the bed 6, I found Tereb. sella, Terehratella 

 astieriana, Bhy. lata, Sky. depressa, and a small Terebratula, that might be a young 

 Ter.faba. The bed No. 11 has produced TerZi. oblongus only; while the beds 12 and 

 13, which contain the same fauna have furnished, Terebratula sella, T. prmlonga, T. 

 tamarindus, T. -pseudo- jurensis, T.faba (2 varieties), T. semistriata, T. Moutoniana, T. 

 collinaria, Terehratella ohlonga, T. reticulata, T. neoconiiensis, Hhynchonella depressa, Rh. 

 lata, Rh. Renauxiana (?), and 4 other species of Rhynchonella, Thecidea tetragona, 

 and a species of Argiope. The beds 16 and 17 contain only T. sella. Now, although 

 I have made use of the specific names adopted by d'Orbigny to the Rh. depressa and 

 Rh. lata that occur in beds 6, 12, and 13, I am persuaded that those from No. 6 are 

 completely distinct, not only as varieties, but also specifically from those that occur 

 in beds 12 and 13, and the same may be stated with reference to the T. pralonga, said 

 to occur in beds 12 and 13. 



