106 



Slepìianodiscus berolinensh, C. G. E. 

 Siirirella ovata, F. T. 1\. 



— stria tuia, T. 



White Terrace, Pyramid Lake, Nevada. 

 Cocconeis placentula, C. G. E. 

 Cyclotella oper culata, C. A, A. 

 Cymbella parva, VV. S. 

 Gomphoiiema intricatum, F. T. K. 

 Melosira undulata, F. T. K. 



— crenulata, F. T. K. 

 Rholcosphenia curvata, F. T. K. 



White beds near Ist point on North shore of Soda Lake. 

 Melosira crenulata, F. T. K. 



Crystals of Calcium Carbonate. 



Pieces of Ilornblende. 



And herein I wish to say that I am indebted to Mess. G. K. 

 Gilbert and J. C. Russell for these specimens which have enabied 

 me to study with the microscope material from Lakes Lahontan, 

 Bonneville and jMono. Bonneville is in Utah, Lahontan is in Nevada 

 and Mono is in California. The two former are fossil lakes only ìi- 

 ving in the imagination of geologists. The last now exists but much 

 smaller than formerly was the case. Lake Bonneville includes Great 

 Salt Lake, Utah and Sevier Lake, which exist now and was a 

 very large lake and had the Wahsatch mountains on the cast. Lake 

 Lahontan includes Pvramid and Winnamucca Lakes and various 

 smaller lakes and had the Sierra Nevada Mountains on the west 

 and no mountains on the cast. Lake Mono is in the southern por- 

 tion of the Great Plain and was, as I have said, much larger than 

 now. The Great Plain is bounded on the west by the Sierra Ne- 

 vada Mountains, on the cast by the Wahsach Mountains. On the 

 north it runs up into British possessions how far it is unknown. On 

 the south it is bounded by the Gulf of California and part by the 

 Gulf of Mexico. So it is large, much larger than any fresh water sea 

 now existing. 



Notwithstanding that Gilbert and Russell maintain that two 

 lakes Bonneville and Lahontain are placed in the Pleistocene, that 

 is to say recent, 1 am stili of opinion that they were formed in the 



