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trating the geology of the eastern base of the Rocky Mountains, 

 and showing the insufficiency of any evidence yet brought in 

 from that region by explorers, as published by Mr. Marcou, for 

 the introduction of a group of rocks of OoUtic or Jurassic age, 

 into the geological map of that geologist, in the district of the 

 Raton Mountains. He inquired of Dr. Jackson, who had inspected 

 Mr. Marcou's specimens, whether any fossils exist to authenticate 

 his views. 



Dr. Jackson replied, that he had no doubt of the fact, that Mr. 

 Marcou possessed abundant evidence to sustain his views with 

 regard to his geological discoveries among the Rocky Mountains. 

 Dr. Jackson had examined his geological map, in which the 

 position of each group of rocks was represented by colors ; he 

 observed the Jurassic and Cretaceous rocks were represented upon 

 that map, and he saw numerous well characterized cretaceous fos- 

 sils, in the collection brought home by Mr. Marcou from the Rocky 

 Mountains. He also had seen a large collection of fossils of 

 the Carboniferous Limestone, amongst which were Spirifer pecos, 

 numerous Producti, and TerehratulcB. Also specimens of Opal- 

 ized Wood, from a petrified forest in the New Red Sandstone, 

 which is seen overlying the Carboniferous rocks. As to the 

 Jurassic rocks, Marcou was especially qualified for correct obser- 

 vations, as he is the author of an admirable Memoire on the 

 Jura Salinois, a work published, in quarto, by the Geological 

 Society of France. Mr. Marcou expects, as soon as his health 

 is restored, to publish his geological map and observations on the 

 geology of his great section across this continent, and since he 

 will have any aid he may need from the most eminent palaeon- 

 tologists of Europe, to whose inspection all his fossils will be 

 submitted, there is not the slightest chance of his falling into 

 any error, with regard to the geological age of the rock forma- 

 tions which he has explored. Mr. Marcou is now sick, and is 

 at Salins, in the Department of the Jura, his home. We shall 

 probably see his Memoire on the Geology of the Rocky Moun- 

 tains, in the Bulletin of the Geological Society of France. 



Dr. A. A. Hayes presented the following communica- 

 tion, on the chemical characters of the water which enters 

 the sea, at some depth below the city of Boston : — 



