1877.] 67 [Hitchcock. 



ice, which coincided with the course of the principal valleys. (Great 

 Ice Age, Amer. ed., pp. 17 and 88.) ; 



Mr. Geikie attributes these different forms of surface of the till to 

 the " varying direction and unequal pressure of the ice- sheet." Prof. 

 N. S. Shaler, in a memoir upon these hills of glacial drift about Bos- 

 ton, has suggested that they are remnants of erosion (Proc. Boston 

 Soc. of Nat. Hist., Vol. xin, p. 196). Alluding to the possibility of 

 this, Mr. Geikie says, " This peculiar configuration of the till, al- 

 though doubtless modified to some extent by rain and streams, yet 

 was no doubt assumed under the ice-sheet." 



As some of these lines of lenticular hills are ten miles long, and 

 most of them on the seaboard are essentially parallel to one another, 

 and adjacent regions destitute of them, we cannot doubt their orig- 

 ination from glacial movements. They are more like lateral mo- 

 raines than any other drift accumulations, or they might be regarded 

 as modifications of one great terminal moraine, reaching from 

 Maine through New Hampshire, eastern Massachusetts, Cape Cod 

 and Long Island to New York. Their marked -absence from certain 

 localities may indicate irregularities in the ^dge of the ice sheet. 



Tlie various features of these hills indicate different and successive 

 movements. There must have been a planing down of the ledges 

 prior to the accumulation of the moraines ; perhaps the same with 

 the glaciation of the districts where the lenticular hills are absent. 

 And lastly, the distribution of loose blocks over their surface in the 

 universal rounding of the hills, appears like the results of local 

 movements connected with the final disappearance of the ice. A 

 few cases of hard pan overlying thick deposits of sand remain to be 

 explored. 



These observations have been made for the New Hampshire 'Geo- 

 logical Survey, in which I have been greatly assisted by Warren 

 Upham. 



A fine bust of Prof. Louis Agassiz, by Mr. Preston Pow- 

 ers, the gift of the Rev. R. C. Waterston, was exhibited, and 

 a vote of thanks to the donor passed. 



A collection of Geodes from Iowa, the gift of Mr. H. S. 

 Smith ; a series of Porphyries from Mr. T. T. Bouve; a col- 

 lection of minerals and products of Queensland, from the 

 Centennial Commission of the Province ; and a work on the 

 Mammals of Australia, from the Australian Commissioner, 



