PHILOSOPHICAL SOCIETY OF WASHINGTON. 27 



Mr. Gill followed, remarking on the combinations of the 

 several faunas ; and dissenting from the views of Mr. Sclater, 

 as stated by Mr. Button. He likewise discussed the extension 

 of warm-water forms northward iu the preglacial epoch, and the 

 extension of cold-water forms southward in the glacial epoch. 



Gen. G. K. Warren, U. S. Engineer, by request, followed 

 with remarks on changes in the interior section of North 

 America, stating that, at some time subsequent to the glacial 

 period, Lake Winnipeg drained to the south, instead of the 

 north, as at present ; and that the northern portion of this region 

 has been depressed. 



Mr. Gale made remarks on the heaps of bowlders, arranged 

 in lines across Manhattan Island and Long Island, passing over 

 ranges of hills ; expressing the opinion that these bowlders must 

 have come from some region more than forty miles distant. 



Mr. Taylor brought up Croll's theory, that when the eccen- 

 tricity of the earth's orbit was at its maximum, a coincidence of 

 the aphelion and winter solstice would greatly increase the cold 

 of northern winters, and thus might be sufficient to produce a 

 glacial period. 



Mr. Abbe remarked on the insufficiency of this to account for 

 the great increase of cold.* 



Mr. Dall gave an account of what he had observed of very 

 great elevations and depressions, at different periods, in the 

 Aleutian Isles and on the Yukon in Alaska. 



81st Meeting. January 30, 1875. 



The President in the Chair. 

 Fifty members and visitors present. 



The President announced the election of Hon. George 

 Bancroft, Dr. Anton Zumbrock, Prof O. T. Mason, Col. S. 

 Thayer Abert, Col. Garrtck Mallery, and Lieut. Henry 

 Jackson as members of the Society. 



