PALEONTOLOGY. 271 



disgrace the Celtic age-; on the other side a saccharoid limestone evi- 

 dently worn away by friction. 



2. The deposits of Tayac and of Tursac (Dordogne) have furnished 

 under the same conditions specimens of granite, squared or rounded 

 at the edges, and hollowed in the centre, intended beyond doubt for 

 grinding grain. In presence of these authentic facts the most philo- 

 sophical course is to refuse our consent to the systematic elimination 

 of these objects from the reputed diluvial beds, and for my own part 

 I cannot a priori reject the theory of their antiquity. 



But before pronouncing an opinion it will be well to recur to the 

 stratigraphic study of caverns and bone-bearing fissures, and all the 

 land-slides — a study which furnishes a powerful test that perhaps has 

 been too frequently neglected. 



I have, like many other persons, explored the valley of the Somme ; 

 this served for a starting point, but it was necessary to proceed in 

 search of new facts, and to correct the observations made in some 

 localities that had been too superficially explored. 



The department of Loir-et-Cher has furnished at a great number of 

 points flint instruments : nuclei, knives, hatchets, spear-points, round 

 or kidney-shaped bails which had served as hammers for making 

 splinters. These different implements are found in the sub-soil, or 

 even at the surface, when they have been turned up by the plough- 

 They invariably accompany the drift so generally seen in Sologne on. 

 the table-lands, and are always met with at points wher% the under- 

 lying geological formations crop out ; at some points, gravels or shell- 

 marl grits, at others the upper limestone beaches of the system of 

 Beauer, and at others chalk layers. 



On the 19th of July, our colleague, M. De Verneuil drew my 

 attention to the same facts near Sacy-le-Grartd, at 120 yards below 

 the level of the Oise. A diluvium covers the lignite-clays of Soison- 

 nais. Here flint splinters bestrew the soil, many of them character- 

 ized by workmanship of considerable fineness of execution. Here, as 

 every where else, (not even excepting the banks of the Somme and 

 the caverns) the traces of a natural polish upon the flints seem to me 

 to deserve a minute examination. Should these traces be attributed 

 to the pressure of blocks driven along by the currents ? The fact is 

 general and demands an explanation. 



The most useful study to undertake is the establishment of a cor- 

 relation between the flint-stones and the animal remains which accom- 

 pany them, when destructive agencies, and especially the dissolvent 



