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THE GEOLOGICAL MAP OF THE WORLD. 349 
discovered a group of extinct volcanoes between the River Gal- 
legos,,Cape Virgins and the eastern entrance of Magellan Straits, 
in Patagonia. Professor Burmeister, Director of the Museo Pub- 
lico of Buenos Ayres, has sent me a manuscript geological map of 
the Argentine Republic, and Mr. David Forbes has published a 
new geological map of a part of Bolivia and Peru, which slightly 
modifies the most complete and detailed one of the late Alcide 
@’ Orbigny. ! 
In Brazil some great modifications and corrections have been 
introduced by the researches of Messrs. Hartt, Coutinho, Chand- 
less and Orton, especially in the basin of the Amazons, and on the 
shore of the Atlantic Ocean. The Devonian and Carboniferous 
formations have been traced to Mont Ereré and to the first Cat- 
aract of the River Tapajos; the Cretaceous formation is found in 
upper Purus, and the Tertiary formation near Pebas on the River 
Marañon. 
Mr. Charles B. Brown has sent me a manuscript geological map 
of English Guiana, the geological survey of which he has directed 
for several years. The same savant published several years ago, 
in collaboration with Mr. J. G. Sawkins, a detailed geological map 
of Jamaica. 
Venezuela and the United States of Columbia, or New Granada, 
have been explored by Messrs. Rogias, Uricoechea and Dr. Maack, 
all of whom have very kindly communicated to me their interest- 
ing and difficult researches. The republics of San Salvador and 
of Guatemala have been explored by the late August Dollfus and 
M. E. de Montserrat, who have given a. geological map of them. 
Finally, Baron F. von Gerolt, for a long time Prussian minister to 
Mexico, has published in New York a geological map of a part 
of the vast plateau, principally of volcanic origin, which extends 
between Puebla, Guerrero, Guanujuato and San Luis Potosi in 
Mexico. ; 
The United States and the British Provinces of North America 
have continued to be the object of numerous researches and geo- 
logical publications. I may signalize especially (1) in Hudson’s 
Bay Territory the explorations of Messrs. J. Hector, Kennicott, 
Hind, Bell and Richardson; (2) the numerous journeys and stud- 
ies of Dr. Hayden on the Upper Missouri; (3) the remarkable 
discoveries of Dr. Newberry in Arizona and New Mexico, of 
srs. C. King, Rémond de Corbineau, H. Engelmann, S. F. 
