The distribution and the description of the petroglyphs of Mexico, as well as of other forms of pictographs found there, are omitted in the present paper. The subject is so vast, and such a large amount of information has already been given to the public concerning it, that it is not considered in this work, which is mainly devoted to the similar productions of the tribes popularly known as North American Indians, although the pre-Columbian inhabitants of Mexico should, in strictness, be included in that category. It is, however, always to be recognized that one of the most important points in the study of pictographs, is the comparison of those of Mexico with those found farther north.
Copies of many petroglyphs found in the eastern hemisphere have been collected, but the limitations of the present paper do not allow of their reproduction or discussion.
While the scope of this work does not contemplate either showing the distribution of the rock carvings in South America, or entering upon any detailed discussion of them, some account is here subjoined for the purpose of indicating the great extent of the ethnic material of this character that is yet to be obtained from that continent. Alexander von Humboldt, in Aspects of Nature in different lands and different climates, etc., Vol. I, pp. 196-201, London, 1850, gives the following general remarks concerning pictographs from South America: