38 Bulletin 15 348 



LimncBa. Usually the bulk of the limestone has been much re- 

 duced by subsequent erosion. lyike the white limestone, although 

 generall}'' of freshwater origin, it comprises also local brackish and 

 marine beds. 



Near Bordeaux, the grey Agen limestone is represented in 

 part by the Saucats limestone. Fossils in this are rare. M. 

 Benoist has found Planorbis solidus, P. dedivis, Helix subglobosa 

 and other species. The surface is bored by Pholas. According 

 to Benoist, the Saucats limestone is the only representative in the 

 Saucats valley of the grey limestone of Agen; but Tournouer, 

 Linder and Fallot include also as equivalents, the shell-marl of 

 I^ariey and the freshwater clayey limestone of the Saucats valley. 



The shell-marl of Lariey. The shell-marl of Lariey is a very 

 compadl, 5'ellowish marl, best observed in an abandoned pit 

 which is not far from the hamlet of Lariey. Cerithhim plicatum, 

 Cytherea undata, Calyptrca sinensis and a number of other species 

 were obtained in abundance by the writer from this locality. 



Liviestone of Le So7i. At Le Son, on a ploughed field, a 

 large number of Ce^'ithiuTn corritgatum and Lidraria sanna were 

 colledled. This locality illustrates well the difficulty of correla- 

 tion in the Bordelais, as on the neighboring field at the same level, 

 are Miocene fossils, and the stratigraphic relations are not 

 revealed by natural seAions. This difficulty is increased by the 

 change of beds laterally and vertically from freshwater to ma- 

 rine faunas. 



Oligocene of the Adour valley. In the valley of the Adour, 

 the Oligocene outcrops in the vicinity of Dax, St. Paul, St. Sever 

 and on either side of the river between St. Avit and Roquefort. 

 Originally these outcrops were very rich in fossils, but now the 

 supply is exhausted. Fortunately there is a fine collecflion of 

 types and specimens from the Adour valley in the museum of the 

 University of Bordeaux. 



Correlation of the Adour marls. The oldest publication on 

 the basin of the Adour was by Palassou,* in 1784. This contains, 



* Essai sur la niintralogie des monts Pyre7iies, Paris, 1784. 



