43 
6 DE MAYo DE 1912. 
Presidencia del Sr. Ing. Leopoldo Salazar Salinas, Vicepresidente. 
TRABAJOS.—Prof. A. M. Carreño. El Chamizal, Chihuahua, (Continua- 
ción). 
Prof. J. Engerrand. El culto de las piedras en el mundo moderno. 
Ing. J. Galindo y Villa. La organización política y municipal del Distrito Fe- 
deral y un Memorandum del Ayuntamiento de Tacubaya. 
Prof. G. Gándara. Técnica para hacer preparaciones microscópicas, según el sis- 
tema de los laboratorios de los Estados Unidos. (Memorias, t. 32, p. 201). 
Prof. A. L. Herrera. Les mouvements browniens son dús d des infusoires co- 
lorables. (Memorias, t. 32, p. 209). 
El Secretario perpetuo, 
R. AGUILAR Y SANTILLÁN. 
A DISCOVERY IN THE POSSIL FIELDS OP MEXICO 
BY 
BARNUM BROWN. 
The State of Jalisco, Mexico, is traversed north and south by low ranges 
of mountains interrupted at intervals by short rivers that flow into the Paci- 
fic. One of these, the Ameca, rises about fifteen kilometera west of Guadala- 
jara in a valley at first open but shut in farther on by low mountains. During 
Pleistocene times the outlet of this valley was blocked long enough to allow a 
shallow lake to be formed in which sediments collected and the remains of many 
animals then inhabiting the country were preserved. These lake and river se- 
diments now appear as terraces of clay, gravel and volcanic debris along the 
foothills. 
Searching the terraces for fossils in the winter of 1910, I found remains 
of several different species of mammals, turtles and fishes, the most interesting 
of all discoveries being a complete carapace of a large glyptodont, an animal 
related to the armadillos. Different genera of glyptodonts existed during Mioce- 
ne, Pliocene and Pleistocene times, ranging in distribution from Patagonia to 
northern Texas, Florida and California, and were especially numerous on the 
