BIBLIOGRAPHY. 
e 
A list of works referred to in the text, as well as of other papers 
devoted especially to the subject of this publication, is here given. 
Those marked with an asterisk I have not been able to consult directly: 
Aguilera, Jose G. and Ordonez, Ezequiel. Expedicion cientifica al Popo- 
catepetl. Mexico, 1895. , 
Baker, Frank C. A Naturalist in Mexico. Chicago, 1895. 
* Boletin de la Sociedad Mexicana de Geografia y Estadistica, Boletin VI, 
Mexico. Since 1850. 
Felix, J. and Lenk, H. Beitrage zur Geologie und Paleontologie der 
Republik Mexico. I Theil, Leipzig, 1890. II Theil, I Heft, Leipzig, 
1893. III Theil, Stuttgart, 1891. 
Fleilprin, Angelo. Barometric Observations among the High Volcanoes of 
Mexico, with a consideration of the culminating point of the North 
American Continent. Proc. Acad. Nat. Sci. of Philadelphia, 1890. 
Philadelphia, 1891. 
Flowarth, O. H. Popocatepetl and the Volcanoes of the Valley of Mexico. 
The Geographical Journal, Vol. VIII, No. 2, p. 137. London, 1896. 
Humboldt, A. Essai Politique sur le Royaume de la Nouvelle Espagne. 
Paris, 1826. 
Ober, Frederick A. Travels in Mexico. Boston, 1887. 
Packard, A. S. Ascent of the Volcano of Popocatepetl. Am. Nat., Feb., 
1886. Philadelphia. 
Pieschel, C. Die Vulcane von Mexico. Zeitschr f.allg. Erdkunde. Bund. 
V, pp. 170 and Igo. _ Berlin, 1885. 
Sonntag, A. Observations on Terrestial Magnetism in Mexico, with notes 
and illustrations of an examination of the Volcano of Popocatepetl and 
its vicinity. Smithsonian Contributions to Knowledge, Vol. XI. Wash- 
ington, 1859. 
* Whitehouse, H, Remise. Alpine Journal, Vol. XV. Nov., 1890. 
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