50 [March 27, 



ported. From this fact, and the general balance of evidence furnished 

 by the fauna, and also from the contraction of the excavation as the 

 valleys became deeper, the author infers a gradual amelioration in 

 the temperature, ending in the present climatal conditions. 



Flint-implements. The author observes that flint-implements are 

 nowhere so abundant in the low- as they are in the high-level gravels. 

 The pointed lance-shaped form with blunt butts of the latter is 

 almost wanting in the former, whereas the ovoid disks of Menche- 

 court are rare at St. Acheul ; again, flakes or flint-knives are com- 

 mon in the low-level gravels and rare in the higher beds. Of the 

 twenty-four specimens found in the low-level gravel at Paris, twenty- 

 two are mere flint-flakes. The author is disposed to attach some 

 value and significance to this difference of form, and observes, that, 

 admitting the climate to have become less severe during the low- 

 level gravel period, it would follow that the necessity of having the 

 strong ice-chisels would have diminished. In all these cases we are of 

 course much limited to conjectures, seeking to make them in accord- 

 ance with what we know of life under like conditions, and guided by 

 the probabilities of the concurring circumstances. The mode of 

 distribution of the flint-implements at the two periods certainly 

 seems to afford some grounds for believing that the difference of form 

 may arise from difference in the pursuits and occupations of the pri- 

 mitive tribes by whom they were used pursuits necessarily and 

 primarily influenced by the climate and life of the period. 



Concluding Remarks. The question of time is then entered upon, 

 and it is shown that the flint-implements must be carried back 

 through the periods of the low- and of the high-level gravels, and 

 that they must be considered to be antecedent to the excavation of 

 many of our great river -valleys. All these phenomena indicate 

 periods of long and great changes. The author only slightly touches 

 upon the formation of the loess, which he concludes to be the result 

 of temporary floods ; and he remarks that, so far as the question of 

 the antiquity of the fluviatile gravels is concerned, little value need 

 be attached to the additional element presented by this covering of 

 loam and brick-earth. This deposit is succeeded by the alluvial 

 beds of the valleys connected more immediately with our own times. 

 "With regard to a measure of time, the author does not consider that 

 either the excavation of the valleys or the life evidence of the periods 



