1882.] 149 [Juhen. 



lower Laurentian age, of chrysolitic lavas or gabbros, now worn 

 down and buried beneath the later sediments, beyond our view. 

 Olivine-sands, it is true, are of rather rare occurrence at the pres- 

 ent time, but only because the chrysolitic rocks are rarely found 

 on the present seacoasts. Such sands do occur in abundance, 

 however, at the Hawaiian Islands, at the foot of the congealed 

 streams of chrysolitic lava which have flowed down to the sea- 

 shore. Aside from the dunytes, there are few rocks, capable of 

 yielding olivine-sands, which now happen to be exj3osed over the 

 territory east of the Mississippi River. However, the number of 

 these, constantly increasing with closer observation (e. g., the 

 huge, erupted masses of chrysolitic rocks near Montreal, and 

 elsewhere in the Province of Quebec, the chrysolitic iron ore of 

 Rhode Island, the chrysolitic hornblende and pyroxene rocks of 

 Cortlandt, New York, the olivine-gabbros of Wisconsin, etc.), all 

 imply that olivine formed by no means an unimportant constitu- 

 ent in the rocks of Archean Age and therefore in the beach-sands 

 of those ancient shores. 



The President gave an account of a trip to Colorado last June ; 

 most of the time was spent at Fairplay, but two or three days 

 were devoted to Florissant. Two new species of fossil butter- 

 flies were found. 



The age of the fossiliferous beds at Fairplay was the particular object 

 of study, as Mr. Lesquereux had maintained that the plants were Permian, 

 while the speaker had concluded the insects indicated a Triassic Age. 

 This view seemed to be seconded by the collection made the present sea- 

 son. Among the finds at Florissant was the stump of an ancient Sequoia 

 44 ft. in circumference. 



General Meeting, December, 20, 1882. 



The President, Mr. S. H. Scudder, in the chair. Seventy- 

 eight persons present. 



The President introduced Miss Alice C. Fletcher, who gave an 

 account of the celebration of the " sun dance " by the Ogallala 

 Indians. 



