304 The American Naturalist. 
ment of that epoch crowning the hills and plateaux in the neig 
hood of the valley. In the valley of the Meuse, M. van den B 
cited evidence to prove that the lower levels were much more : 
than the high levels. Localities cited by M. Mourlon were not 
Plistocene, because both were situated on the flank of the valley, an 
not on the Plistocene of the plateaux. The fauna of a cavern 
only be the same as that of the valley. 
Mr. John Evans was in accord with those who said that the 
valleys had been cut before the Plistocene, but we should not f 
that there may be valleys of all epochs. He approved the o 
and conclusions of Prestwich, but only in regard to that which c 
cerns the Plistocene, and said that neither himself nor other gec 
gists of England could follow Mr. Prestwich in his theory o 
worked flint being pre-Glacial. In his opinion the d 
worked flint at Igtham was a superposition well established. 
omas Wilson said a few words upon the progress 
American geologists on the subject of the Plistocene period 
discovered on the surface in his country, as had been those 
implements found by Mr. Prestwich at the locality of Igtham i 
On the subject of the cutting of the valleys and their su 
filling, he remarked that the rivers of France and England es 
have been carried out to its conclusion by the courses of 
he invited the geologists of Europe who were interested in st 
this question not to neglect the opportunity of visiting 
States upon the occasion of the next geologic congress, to 
1891, that they might investigate our rivers; those flowmg 
mountains to the Atlantic seaboard, some of them passing thr 
glacial moraine, like the Connecticut, Hudson, and Delaware, ¢ 
others coming from mountains unaffected by the glaciers, as tae 
quehanna, Potomac, and James ; or go to the west, where ’ 
found rivers from 1,000 to 4,000 miles in length, as the Ol 
land, Tennessee, Mississippi, and Missouri, on the banks 
_ to be found cut the same kind of caverns as those of Be 
also the terraces of the high, low, and middle levels of F 
grand, and Mortillet; they were thus to be found, not 
Positions, but stretched out for hundreds of miles. ‘The earth 
one place would be carried to another further down, and 
and redeposited many, many times before reaching the 0c 
