82 



N. 5. Geyser Basin, Geysers of Fire Hole River, Yellowstone 

 Reservation. Aug. 71. 



N. 6. Steamboat Point, N. E. corner of Yellowstone Lake, 

 Aug. 19. 71. 



N. 7. Chalk Beds, Fossil Station, C. P. R. R. 



N. 8. Marsh Cr. Valley, June 17. 71. 



N. 9. Hot Spring, Geyser Basin, Geysers of the Fire (Jole River, 

 Yellowstone Reservation. Aug. 3. 71. 



N. io. East Shore, Yellowstone Lake. 



N. 11. Geyser Basin, Geyser of the Fire I Iole River, Yellowstone 

 Reservation. Aug. 3. 71. 



N. 12. Hot Springs, West Shore of Yellowstone Lake. Aug. 9. 71. 



N. i3. Geyser Basin, Geysers of Fire Hole River, Yellowstone 

 Reservation. Aug. 3. 71. 



N. 14. Chalk Beds, Hot Springs, C. P. R. R. 



N. i5. Granite Canon, Oct. 18. 69. 



N. io. Chalk Beds between White Plains and Hot Spring Sta- 

 tion. Nov. 3. 71. 



Of these I have partial note of the examination of the speci- 

 mens that went away to the San Francisco Microscopical Society 

 where they are now. The examination was as follows. 



N. 1. An extremely fine white sand, siliceous in composition 

 and apparently of volcanic origin but containing no remains of or- 

 ganic forms by means of which its mode of formation can be ascer- 

 tained with definiteness. I say apparently of volcanic origin for it 

 contains grains of a form by means of which I have for a number 

 of years in the habit of considering as resulting from the breaking up 

 of pumice when it has fallen in the hot state into cold water. These 

 particles do not polarise light and therefore are of colloid silica. 

 Therc are no organic forms present in the specimen so it can be 

 considered as light pumice thrown out by a volcano. It was formed 

 from clay which subjected to a very high heat, much higher than 

 we can ordinarily subject it to. 



N. 2. A fine sand having upon it small quantities, and for the 



most part broken, a few fresh water Confervae and Bacillaria be- 



longing to common species, as Epìthemia gibba. E. , Nicchia 



Pinnularia major, P. , Himantidìum , 



