The account here given of experiences resulting in a discovery so surprising, must interest even those sceptical in regard to the progress in art of the American aborigines; and it must also be remembered that, almost without exception, late as well as early travellers in this region have become enthusiastic and imaginative when brought into contact with these monuments of a measureless past,[63-*]--none of them more so, perhaps, than Brasseur de Bourbourg, whose works nevertheless contain a mine of most valuable information aside from hypotheses. Accompanying the Memorial, a set of photographs, some of them similar to those copied in heliotype, was sent to Mexico for the information of the President, but the numbers in the last pages of that paper, referring to the special set of photographs, do not correspond to the pictures presented here, as there were no means of verifying the subjects, except from the descriptions. NOTE.--It will be observed that Dr. Le Plongeon’s spelling of the word _Chac-Mool_, differs from that adopted by the writer in deference to prevailing usage in Yucatan. The discoverer always spells the word _Chaacmol_, although in the long letter to the writer, on the subject of Maya antiquities, introduced at the close of this paper, the more usual spelling has been adopted by the printer, contrary to the text of Dr. Le Plongeon. MEMORIAL PRESENTED TO THE MEXICAN GOVERNMENT, AND AFTERWARDS PUBLISHED IN THE OFFICIAL JOURNAL OF YUCATAN, APRIL 19 AND 21, 1876. _To the President of the Mexican Republic_, SENOR DON SEBASTIAN LERDO DE TEJADA. Sir: I, AUGUSTUS LE PLONGEON, Doctor in Medicine, member of the Academy of Sciences of the State of California, of the Microscopical Society of San Francisco, of the Philological Society of New York, corresponding member of the Geographical and Statistical Society of Mexico; and of various other scientific societies of Europe, of the United States of America, and of South America; citizen of the United States of America; resident at present in Mérida, Capital of the State of Yucatan, to you, with due respect, say: Since the year 1861 I am dedicated to the iconology of American antiquities, with the object of publishing a work that may make known to the world the precious archæological treasures that the regions of the so-called new world enclose, nearly unknown to the wise men of Europe, and even to those of America itself, and thus follow the perigrinations of the human race upon the planet that we inhabit. With so important an object, I visited the different countries of the American Continent, where I could gather the necessary information to carry through my work, already commenced, and in part published, “The Vestiges of the human race in the American Continent since the most remote times.”