500 The American Naturalist. [May, 
Monsieur Gabriel de Mortillet spoke of the glacial phenomena as 
being divided into two groups: the one at the far north, and the other 
in the Alps, Pyrenees, etc., in the south. The Alps and glacial phe- 
nomena could have been produced by only one cause, that of the 
increased cold, and this cause would at the same time produce an exten- 
sion of the glaciers of the north. He might admit the fluctuations, 
oscillation, retreat and advance, appearance and disappearance of the 
glaciers, but this was far from admitting a plurality of glacial periods, 
and was contrary to this idea. 
M. Marcellin Boule took up the question and gave a detailed de- 
scription of European glaciers. After late investigations the epochs of 
the glaciers of the north and of the Alps could not be separated, and 
geologists were not in accord in opposing the ancient hypothesis of 
the Plistocene sea of floating ice. The grand glacier coming down — 
and through Scandinavia had attained to Erzgebirge, where it had de- 
posited erratic blocks geschicbelehm. This was followed by a retreat 
corresponding to the melting and opening of the North and Baltic 
Seas, during which time was deposited the interglacial alluvium, with a 
fauna of a warm country. Alluvium deposits of this epoch were so 
extensive that they measured in Brandenburg alone a surface of 200,- 
ooo square miles, German. In the Alps the deposits of interglacial 
plant at Innsbruck are found at ooo metres of altitude, at the very 
top of the chain of mountains. As for paleontology, M. Boule 
declared that the stratigraphic facts must dominate, though he doubted 
the pretended facts of stratigraphy as given by some of the investiga- 
tors, though he was far from saying that the fauna and flora of the 
Upper Pliocene, the Plistocene, affected detrimentally or were in opp 
sition to the facts found by stratigraphy. MM. Bleicher and Fliche 
have just described to the Geologic Society of France a deposit in the 
northeast of France, in the plants and mollusks demonstrating the 
alternating epochs of cold and heat. 4 
Third Question: ‘Art and Industry during the Paleolithic Period 
—in the Caverns.’’ 
Judge Piette, of Angers, who probably headed the list of cavern 
investigators in France, had displayed at the great exposition his mag- 
nificent and extensive collection, principal among which were his late 
finds in the cavern of Mas d’Azil, on the river Avise, in the Depart 
ment of Ariège, and so he was entitled par excellence to lead in the 
discussion. He gave a description of these latest. discoveries, the 
results of three years’ continuous labor in Mas d’Azil, and present 
his opinions and conclusions deduced from a study and comparison 
