502 J. F. BLAKE ON THE UPPEE 



Pig. 1. — Map of Country near Neuvizy. (Scale 1 : 80,000.) 



by the term ' terrain a chailles'**, contain a characteristic fauna, viz. 

 Ammonites cordatus, Modiola bipartita, Perna quadrata, Pecten ji- 

 brosus,Aviculaexpansa, Exogyra spiralis, Ostrea dilatata, 0. rastellaris 

 Bhynehonella Thurmanni, and several others less certainly identified, 

 but all indicating a horizon similar to that of the No the grits and 

 clays or of the Lower Calcareons Grit of Yorkshire. At the top this 

 series becomes much more calcareous, and finally contains abundant 

 oolitic grains, while a change of fauna takes place. This has been 

 very imperfectly examined ; but the three chief species are Ammo- 



* This term " terrain a chailles" is a misleading one. It is often used as if 

 indicating a fixed horizon ; but it appears from French writers that there is one 

 of these ' terrains ' in the Oallovian, another in the Oxfordian (the present 

 one), and a third in the Corailian ; so that it is really a mere petrologieal phrase 

 similar to " nodular beds ". 



