Mr. J. Prestwich on the Drift Deposits. 63 



lopment of the group is rather in a northern than in a southern 

 direction. 



The several genera and species of Mammalia are then considered, 

 the principal being Elephas primigenius, Rhinoceros tichorhinus, Bi- 

 son priscus, with several species of Equus, Bos, Cervus, whilst the 

 Reindeer is found in deposits of the same period ; and an opinion is 

 expressed that the evidence with respect to the climatal conditions 

 furnished by the Mammalia, although slight, is more definite than 

 that obtained from the Mollusca, and tends to show the probability 

 of the climate at the period of the high-level gravel having been 

 colder than that of these latitudes at the present day. The flora is 

 scanty and of little avail. It is then remarked that if we had to 

 depend only upon the organic remains for decisive evidence of the 

 nature of the climate of the period under inquiry, we should at 

 present fail to arrive at any safe and exact conclusion. If, however, 

 these indications are taken in conjunction with the physical features, 

 the conjoint evidence has weight and more preciseness; and the author 

 concludes, from a review of all the facts, that there must have been 

 a mean winter cold of not less than 20°, and possibly as low as 10°, 

 or from 19° to 29° below the mean winter temperature (39°) of this 

 part of Europe. The cave evidence would have helped this question. 



The Flint-Implements. — These works of man are first discovered 

 in beds of the high-level gravel period. The most ordinary shapes 

 are the large spear-head form, either with a sharp point or a flat 

 rounded one, and with the butt end sometimes blunt, and at other 

 times chipped to an edge. "With regard to the manner in which 

 they came to be imbedded in the gravel, it can only be surmised 

 from their condition, from our present experience, and by considering 

 the uses to which they could possibly have been applied. 



These conditions are then reviewed, and it is shown that the flint- 

 implements rarely or never show indications of atmospheric weather- 

 ing ; that they are rarely worn, but are usually sharp and angular, 

 like some of the large unworn flints which have been attributed to 

 transport by ice ; also that they are most common where the evi- 

 dence of ice-action is the greatest, as at St. Acheul and Moulin 

 Quignon. The climate of the period having been severe, it is essen- 

 tial to keep in mind the usages of tribes under like conditions at the 

 present day. The mode of life of the Chipweyan Indians and the 

 Esquimaux is then considered ; and it is shown that a hatchet, an 

 ice-chisel, a file and knives, of stone or metal, are all the instruments 

 they need or use. It is further shown that when in winter the 

 usually abundant supplies of Reindeer fail, these people resort com- 

 monly to fishing in the frozen rivers, and then use their ice-chisels 

 for making holes in the ice. These implements are also in daily use 

 for keeping open the water-holes. Analogous facts are quoted from 

 "Wrangel respecting Siberia. The author suggests therefore that 

 some of the mysterious flint-implements (such as fig. 5, pi. 12, Phil. 

 Trans. 1860) of St. Acheul may have been used as ice-chisels. Rea- 

 sons are then assigned for their presence chiefly at particular spots ; 

 and reference is made to other forms of flint-implements, all of which 



